# ToolVault 工具匣

> Free online developer toolkit with 132 privacy-first tools — JSON formatting, JWT decoding, hashing, regex testing, encoders, code formatters and more. Everything runs locally in your browser: no registration, no uploads, no tracking. https://www.wcytcn.com

ToolVault is a privacy-first, pure frontend developer toolkit. All tools run locally in the browser — data never leaves the device. Bilingual (Chinese / English), free, no sign-up. This file lists every tool; see llms-full.txt for complete per-tool FAQ content.

## Tools (132)

### Utility Tools (46)

- [Color Converter](https://www.wcytcn.com/en/tools/color-converter): Free online color converter for HEX, RGB, and HSL with alpha channel support. Essential tool for designers and frontend developers. Runs locally in your browser.
- [Password Generator](https://www.wcytcn.com/en/tools/password-generator): Free secure password generator using crypto.getRandomValues for true randomness. Customizable length, uppercase, lowercase, numbers, and symbols. Generated locally, never stored or uploaded.
- [Timestamp Converter](https://www.wcytcn.com/en/tools/timestamp-converter): Free online Unix timestamp converter with auto-detection of seconds, milliseconds, and microseconds. Supports Local, UTC, ISO 8601, and relative time conversion. Runs locally in browser.
- [Cron Expression Parser](https://www.wcytcn.com/en/tools/cron-parser): Free online Cron expression parser. Input a 5-field Cron to get a human-readable description. Supports step values, ranges, and lists. Runs locally, no registration required.
- [CIDR Calculator](https://www.wcytcn.com/en/tools/cidr-calculator): Free online IPv4 CIDR subnet calculator. Input IP and prefix to compute network address, broadcast, subnet mask, host range, and available hosts. Runs locally in browser.
- [Text Diff Tool](https://www.wcytcn.com/en/tools/text-diff): Free online text diff tool using LCS algorithm for line-by-line comparison. Highlights additions, deletions, and modifications. Powered by Monaco DiffEditor with syntax highlighting, runs locally.
- [Number Base Converter](https://www.wcytcn.com/en/tools/number-base-converter): Free online number base converter supporting binary, octal, decimal, and hexadecimal. Convert between all four bases instantly. Runs locally in your browser, no registration required.
- [Word Counter](https://www.wcytcn.com/en/tools/word-counter): Free online text statistics tool for real-time counting of characters, words, lines, sentences, and paragraphs. Supports both Chinese and English text, runs locally in browser.
- [Case Converter](https://www.wcytcn.com/en/tools/case-converter): Free online text case converter supporting UPPER CASE, lower case, Title Case, camelCase, snake_case, kebab-case, and CONSTANT_CASE. Runs locally in your browser, no registration required.
- [QR Code Generator](https://www.wcytcn.com/en/tools/qr-code-generator): Free online QR code generator. Enter URL or text to create a QR code with custom size and error correction level. Download as PNG. Generated locally, no registration.
- [Lorem Ipsum Generator](https://www.wcytcn.com/en/tools/lorem-ipsum-generator): Free Lorem Ipsum placeholder text generator. Generate by paragraphs, sentences, or words with classic opening mode, runs locally in your browser.
- [HTTP Status Codes Reference](https://www.wcytcn.com/en/tools/http-status-codes): Free HTTP status codes reference covering all 1xx-5xx codes with descriptions and usage scenarios. Fully offline, no registration required.
- [URL Parameter Parser](https://www.wcytcn.com/en/tools/url-params-parser): Free URL params parser that splits protocol, host, query, and hash with auto-decoding and array parameter support, runs locally in your browser.
- [Cron Expression Generator](https://www.wcytcn.com/en/tools/cron-generator): Free visual Cron expression generator. Select timing to auto-generate 5-field Cron with human-readable description, runs locally in your browser.
- [Online QR Code Decoder](https://www.wcytcn.com/en/tools/qr-code-decoder): Free QR code decoder supporting drag-and-drop and paste. Powered by jsQR for local decoding, images are never uploaded to any server.
- [Regular Expression Explainer](https://www.wcytcn.com/en/tools/regex-explainer): Free regex explainer that breaks down regex syntax segment by segment with annotations. Supports lookarounds and named groups, runs locally.
- [Text Deduplication Tool](https://www.wcytcn.com/en/tools/text-dedupe): Free text deduplication tool for line-based dedup. Supports case sensitivity, whitespace trimming, and first/last occurrence order, runs locally.
- [User-Agent Parser](https://www.wcytcn.com/en/tools/user-agent-parser): Free User-Agent parser that extracts browser, OS, device type, and CPU architecture. Runs locally in your browser, no registration required.
- [Byte Unit Converter](https://www.wcytcn.com/en/tools/byte-converter): Quick conversion between byte, KB, MB, GB, TB and other storage units, supporting both decimal (1000) and binary (1024) standards.
- [Color Palette Generator](https://www.wcytcn.com/en/tools/color-palette-generator): Free color palette generator supporting complementary, analogous, triadic, and more. Scientifically generated via HSL color space, runs locally.
- [IP Subnet Calculator](https://www.wcytcn.com/en/tools/subnet-calculator): Free IP subnet calculator. Divide by subnet count or host count with automatic mask and address range calculation, runs locally in your browser.
- [HTTP Request Method Cheatsheet](https://www.wcytcn.com/en/tools/http-method-cheatsheet): Free HTTP method cheatsheet covering GET, POST, PUT, DELETE, PATCH, and more. Annotates idempotency and safety, fully available offline.
- [Text Sort Tool](https://www.wcytcn.com/en/tools/text-sort): Free text sort tool supporting ascending, descending, by length, natural sort, and shuffle with customizable rules, runs locally in your browser.
- [Number Base Converter Advanced](https://www.wcytcn.com/en/tools/number-base-advanced): Free advanced number base converter supporting any base from 2 to 36, floating-point conversion, and IEEE 754 representation, runs locally.
- [Text Extractor Tool](https://www.wcytcn.com/en/tools/text-extractor): Free text extraction tool to extract emails, phone numbers, URLs, IPs, ID numbers and more with one click. Supports custom regex, runs locally with no data leakage.
- [Text Replace Tool](https://www.wcytcn.com/en/tools/text-replace): Free online text replace tool with regex support, case insensitivity, and capture group references. Batch find and replace text, runs locally with no registration required.
- [Line Batch Processor](https://www.wcytcn.com/en/tools/line-batch-processor): Free line batch processor supporting prefix/suffix, remove empty lines, line numbers, dedupe, reverse, filter and sort. Process text lines in one click, runs locally.
- [Markdown Table Generator](https://www.wcytcn.com/en/tools/markdown-table-generator): Free Markdown table generator with visual editing, CSV import/export, and column alignment settings. Create professional tables quickly, runs locally with no registration.
- [URL Parser & Builder](https://www.wcytcn.com/en/tools/url-parser): Free online URL parser and builder that breaks down protocol/domain/path/params/hash with visual query parameter editing and real-time two-way sync. Runs locally in your browser, no registration required.
- [Color Contrast Checker](https://www.wcytcn.com/en/tools/color-contrast-checker): Free online color contrast checker that validates WCAG AA/AAA accessibility standards, auto-suggests accessible colors with real-time preview. Runs locally in your browser, no registration required.
- [Image to ASCII Art](https://www.wcytcn.com/en/tools/ascii-art-generator): Free online image to ASCII art converter with monochrome/color modes, adjustable width and character sets. All processing is local in-browser with no uploads, protecting your privacy.
- [QR Code Designer](https://www.wcytcn.com/en/tools/qr-code-designer): Free online QR code designer with custom colors, corner styles, and dot shapes. Supports PNG and SVG download. Create unique personalized QR codes generated locally, no registration required.
- [Markdown TOC Generator](https://www.wcytcn.com/en/tools/markdown-toc-generator): Free online Markdown table of contents generator that auto-parses headings to create TOC. Supports GitHub/GitLab anchor formats, custom heading level range, ordered/unordered list toggle. Runs locally with no data leakage.
- [Character Frequency Analyzer](https://www.wcytcn.com/en/tools/char-frequency): Free online character frequency analyzer. Count character occurrences and percentages in text, toggle case sensitivity and whitespace inclusion, sort by frequency or alphabet, export to CSV. Processed locally, no uploads.
- [Text Reverser](https://www.wcytcn.com/en/tools/text-reverser): Free online text reverser with three modes: reverse by characters, words, or lines. Correctly handles multi-byte characters including CJK and Emoji. Real-time preview, one-click copy, all processed locally with no uploads.
- [Slug Generator](https://www.wcytcn.com/en/tools/slug-generator): Free online URL slug generator that converts titles into SEO-friendly URL identifiers. Supports hyphen or underscore separators, lowercase toggle, CJK character preservation, and automatic special character cleanup. Runs locally with no data leakage.
- [CSS Unit Converter](https://www.wcytcn.com/en/tools/css-unit-converter): Free online CSS unit converter supporting px, rem, em, pt, and vw with customizable root font size and viewport width. Enter one value to see all conversions at once. Processed locally, no uploads.
- [Whitespace Remover](https://www.wcytcn.com/en/tools/whitespace-remover): Free online whitespace remover with four combinable modes: trim leading/trailing spaces, remove empty lines, collapse consecutive spaces, and strip all whitespace. Essential for text cleanup. Runs locally, no data leakage.
- [Meta Tag Pixel Checker](https://www.wcytcn.com/en/tools/meta-tag-pixel-checker): Free online meta tag pixel checker that measures Title and Description width in pixels against Google SERP truncation limits, with realistic search result preview. An SEO essential. Runs locally.
- [Open Graph Previewer](https://www.wcytcn.com/en/tools/open-graph-previewer): Free online Open Graph previewer. Enter OG tag content and instantly preview share cards on Facebook, Twitter, and LinkedIn to catch truncation and image ratio issues. Local processing only.
- [Sitemap Generator](https://www.wcytcn.com/en/tools/sitemap-generator): Free online sitemap generator. Paste a URL list to generate a standard XML sitemap in one click, with changefreq and priority options. Download and submit to search engines. Runs locally.
- [robots.txt Generator](https://www.wcytcn.com/en/tools/robots-txt-generator): Free online robots.txt generator. Configure User-agent and Allow/Disallow rules to generate a standards-compliant robots.txt, with sitemap declaration support. Search crawler control made easy. Local processing.
- [Color Blindness Simulator](https://www.wcytcn.com/en/tools/color-blindness-simulator): Free online color blindness simulator that renders how colors appear under protanopia, deuteranopia, tritanopia, and more. Enter any color for instant comparison. Essential for accessible design. Local processing.
- [Tailwind Color Finder](https://www.wcytcn.com/en/tools/tailwind-color-finder): Free online Tailwind color finder. Enter any HEX value to match the closest Tailwind CSS palette color, with delta-E difference and the exact class name. A must-have for frontend styling. Runs locally.
- [Image Color Extractor](https://www.wcytcn.com/en/tools/image-color-extractor): Free online image color extractor. Upload an image to auto-extract dominant colors into an 8-color palette with HEX values. Drag-and-drop and paste supported. Images processed locally, never uploaded.
- [Diff Summary Tool](https://www.wcytcn.com/en/tools/diff-summary): Auto-categorize diff scope, produce add/remove stats and prose summary; optional LLM-backed prose.

### JSON Tools (6)

- [JSON Formatter](https://www.wcytcn.com/en/tools/json-formatter): Free online JSON formatter to beautify, minify, and validate. One-click convert to TypeScript, Go, and Java. Unicode-safe with full Chinese and Emoji support, runs locally.
- [JSON Diff Tool](https://www.wcytcn.com/en/tools/json-diff): Free online JSON diff tool with recursive comparison of nested objects and arrays. Tree-view diff highlighting, semantic structural comparison, runs locally.
- [JSON to CSV Converter](https://www.wcytcn.com/en/tools/json-csv-converter): Free online JSON and CSV converter with automatic nested object flattening and type inference. Easy Excel import, runs locally in your browser.
- [JSON Flattener](https://www.wcytcn.com/en/tools/json-flatten): Flatten nested JSON into key-value pairs or restore flattened JSON back to nested structure, with custom separator support for data processing and debugging.
- [JSONPath Generator](https://www.wcytcn.com/en/tools/jsonpath-generator): Free JSONPath generator that auto-generates path expressions by clicking JSON tree nodes. Pairs with jsonpath-query, runs locally in your browser.
- [JSON Sorter](https://www.wcytcn.com/en/tools/json-sorter): Free online JSON key sorter that arranges object keys in ascending or descending order with optional recursive sorting of nested structures. Values stay untouched for easy diffing and code review. Processed locally, no uploads.

### Data Tools (28)

- [Markdown Preview](https://www.wcytcn.com/en/tools/markdown-preview): Free online Markdown live preview with full GFM support including tables, code blocks, lists, and links. Renders locally in your browser, no registration required.
- [YAML JSON Converter](https://www.wcytcn.com/en/tools/yaml-json-converter): Free online YAML and JSON bidirectional converter. Convert YAML to JSON or JSON to YAML while preserving data structure. Supports nested objects and arrays, runs locally.
- [JSONPath Query Tool](https://www.wcytcn.com/en/tools/jsonpath-query): Free online JSONPath query tool to extract fields from JSON data. Supports filters, recursive descent, and wildcards. All processing runs locally in your browser, no registration needed.
- [JSON Schema Validator](https://www.wcytcn.com/en/tools/json-schema-validator): Free online JSON Schema validator. Validate JSON data against schema definitions with format checks, type checking, and required field verification. Runs locally in your browser, no registration.
- [JSON Schema Generator](https://www.wcytcn.com/en/tools/json-schema-generator): Free online JSON Schema generator. Paste JSON and automatically generate the corresponding JSON Schema definition with nested object and array support and type inference. Runs locally in your browser, no registration.
- [CSV to SQL / Markdown / HTML](https://www.wcytcn.com/en/tools/csv-sql): Free CSV SQL query tool powered by SQL.js (SQLite WASM). Supports SELECT, JOIN, and aggregate functions. All data stays in your browser, no registration.
- [Online JSON to YAML Converter](https://www.wcytcn.com/en/tools/json-yaml-converter): Free online JSON and YAML bidirectional converter. Preserves data structure with nested object and array support, runs locally in your browser.
- [HTML to Markdown Online Converter](https://www.wcytcn.com/en/tools/html-markdown-converter): Free online HTML and Markdown bidirectional converter with GFM extended syntax support. Ideal for content extraction and rendering, runs locally.
- [XML to JSON Online Converter](https://www.wcytcn.com/en/tools/xml-json-converter): Free online XML and JSON bidirectional converter. Correctly handles attributes, namespaces, and CDATA, runs locally in your browser.
- [CSV Data Visualization](https://www.wcytcn.com/en/tools/csv-visualize): Free online CSV data visualization tool with table view and chart support (bar/line/pie charts). Auto-detects numeric columns with real-time preview. Processed locally, no data leakage.
- [Timeline Visualization](https://www.wcytcn.com/en/tools/timeline-visualizer): Free online timeline visualizer that converts event lists to timelines. Supports custom time range and display granularity with horizontal/vertical layout options. Processed locally, no uploads.
- [JSON Schema Editor](https://www.wcytcn.com/en/tools/json-schema-editor): Free online JSON Schema editor for visually building schema structures. Supports property type selection, required field settings, format constraints, and real-time validation. Runs locally with no data leakage.
- [CSV/TSV Converter](https://www.wcytcn.com/en/tools/csv-tsv-converter): Free online CSV/TSV/JSON/Markdown format converter. RFC 4180-compliant quoting and newline handling, custom delimiters and header options, runs locally with no data leakage.
- [Excel to CSV](https://www.wcytcn.com/en/tools/excel-to-csv): Free online Excel to CSV converter. Parse .xlsx/.xls files and export standard CSV with multi-sheet selection and separator options. Automatic quote escaping included. Files never leave your browser.
- [Excel to JSON](https://www.wcytcn.com/en/tools/excel-to-json): Free online Excel to JSON converter that turns spreadsheet rows into JSON object arrays with headers as keys. Supports multiple sheets and nested structures. Ideal for API development, parsed entirely locally.
- [Excel to HTML Table](https://www.wcytcn.com/en/tools/excel-to-html): Free online Excel to HTML table converter that renders worksheets as styled HTML tables, preserving header structure and alignment. Ready to embed in web pages or emails. Files parsed locally, never uploaded.
- [Excel to Markdown Table](https://www.wcytcn.com/en/tools/excel-to-markdown): Free online Excel to Markdown table converter. Turn any worksheet into pipe-table syntax with one click, with multi-sheet switching. Paste directly into READMEs, docs, and issues. All processed locally.
- [CSV to Excel](https://www.wcytcn.com/en/tools/csv-to-excel): Free online CSV to Excel converter that exports CSV data as .xlsx files with custom sheet names and separators. Columns are auto-detected and the file downloads instantly, all in your browser.
- [JSON to Excel](https://www.wcytcn.com/en/tools/json-to-excel): Free online JSON to Excel converter that exports JSON object arrays as .xlsx files. Field names are auto-inferred as header columns with nested data flattening. Instant download, processed locally.
- [Markdown Table to CSV](https://www.wcytcn.com/en/tools/markdown-table-to-csv): Free online Markdown table to CSV converter. Parse pipe-delimited table syntax, extract headers and rows into standard CSV with automatic quote escaping. Essential for doc migration and data cleanup. Runs locally.
- [Markdown Table to JSON](https://www.wcytcn.com/en/tools/markdown-table-to-json): Free online Markdown table to JSON converter that transforms tables into JSON object arrays, using the first row as keys and the rest as values. Great for API work and further processing. Runs locally.
- [Markdown Table to SQL](https://www.wcytcn.com/en/tools/markdown-table-to-sql): Free online Markdown table to SQL converter that turns table data into INSERT statements with auto-generated CREATE TABLE scripts and custom table names. Fast path from docs to database. Processed locally.
- [HTML Table to CSV](https://www.wcytcn.com/en/tools/html-table-to-csv): Free online HTML table to CSV converter. Extract data from table/tr/td elements in HTML fragments into standard CSV, supporting complex structures and quote escaping. Web scraping essential. Runs locally.
- [HTML Table to JSON](https://www.wcytcn.com/en/tools/html-table-to-json): Free online HTML table to JSON converter that parses HTML tables into JSON object arrays with header cells as keys and data cells as values. Essential for structuring web data. Local processing only.
- [HTML Table to Markdown](https://www.wcytcn.com/en/tools/html-table-to-markdown): Free online HTML table to Markdown converter that transforms table elements into Markdown table syntax while preserving structure and alignment. Perfect for READMEs and technical docs. Runs locally.
- [CSV Generator](https://www.wcytcn.com/en/tools/csv-generator): Free online CSV generator. Create sample CSV data with headers in one click by customizing row and column counts, separators, and quoting. Ideal for testing, demos, and mock data. Runs locally.
- [JSON Generator](https://www.wcytcn.com/en/tools/json-generator): Free online JSON generator. Produce sample JSON arrays in one click with custom row and field counts and diversified value types. Ideal for API testing, mock data, and frontend development. Local processing.
- [SQL Mock Query](https://www.wcytcn.com/en/tools/sql-playground): SQL mock engine with users/orders/products sample tables and SELECT/JOIN/aggregate support.

### Code Tools (22)

- [Code Formatter](https://www.wcytcn.com/en/tools/code-formatter): Free online code formatter powered by Prettier. Supports JavaScript, HTML, CSS, and SQL formatting with safe minification. Protects string literals from being broken, runs locally.
- [SQL Formatter](https://www.wcytcn.com/en/tools/sql-formatter): Free online SQL formatter supporting MySQL, PostgreSQL, SQL Server, and more. Custom indent and keyword casing, runs locally in your browser.
- [HTML Minifier / Formatter](https://www.wcytcn.com/en/tools/html-minifier): Free online HTML minifier that removes comments and whitespace while safely preserving script and style content. Reduces file size, runs locally.
- [CSS Minifier / Formatter](https://www.wcytcn.com/en/tools/css-minifier): Free online CSS minifier that removes comments and whitespace, shortens color values, and optimizes shorthand properties. Significantly reduces CSS size, runs locally.
- [JS Minifier / Formatter](https://www.wcytcn.com/en/tools/js-minifier): Free online JavaScript minifier powered by Terser with ES6+ support. Shortens variable names and tree-shakes unused code safely, runs locally in your browser.
- [Dockerfile Generator](https://www.wcytcn.com/en/tools/dockerfile-generator): Free Dockerfile generator with templates for Node, Python, Java, Go, and more. Follows multi-stage build best practices, runs locally in your browser.
- [CSS Gradient Generator](https://www.wcytcn.com/en/tools/css-gradient-generator): Free CSS gradient generator supporting linear, radial, and conic gradients. Custom angle and color stops with real-time preview and copyable code.
- [Mock Data Generator](https://www.wcytcn.com/en/tools/mock-data-generator): Free mock data generator with 28 data types and JSON/CSV/TSV/YAML formats. Batch generate test data, runs locally in your browser, no registration required.
- [JSON to TypeScript](https://www.wcytcn.com/en/tools/json-to-typescript): Free JSON to TypeScript interface tool. Auto-generate interface and type with smart type inference, supports nested objects and arrays.
- [JSON to Go Struct](https://www.wcytcn.com/en/tools/json-to-go): Free JSON to Go Struct tool. Auto-generate struct definitions with json tag and omitempty support, nested objects and arrays. Runs locally in your browser.
- [Java Object to JSON](https://www.wcytcn.com/en/tools/java-to-json): Convert Java object toString() output to standard JSON
- [JSON to Java Class](https://www.wcytcn.com/en/tools/json-to-java): Free JSON to Java Class tool. Auto-generate POJO classes with getter/setter/Lombok/Jackson annotation support. Runs locally with no data leakage.
- [.gitignore Generator](https://www.wcytcn.com/en/tools/gitignore-generator): Free .gitignore generator with 20+ language/framework/IDE templates and custom rules. Generate ignore file configurations in one click, runs locally.
- [CSS Flexbox Generator](https://www.wcytcn.com/en/tools/flexbox-generator): Free online CSS Flexbox generator with visual adjustment of flex-direction, justify-content, align-items and more. Real-time preview with one-click CSS copy.
- [CSS Grid Generator](https://www.wcytcn.com/en/tools/grid-generator): Free online CSS Grid generator with visual adjustment of grid rows, columns, gaps, and alignment. Real-time layout preview with one-click standard CSS copy.
- [SQL Table Generator](https://www.wcytcn.com/en/tools/sql-table-generator): Free online SQL CREATE TABLE generator with visual table structure design. Supports MySQL, PostgreSQL, and SQLite dialects. Generate CREATE TABLE statements in one click, runs locally with no data leakage.
- [HTML to JSX Converter](https://www.wcytcn.com/en/tools/html-to-jsx): Free online HTML to JSX converter. Automatically converts class to className, for to htmlFor, and inline styles to React style objects. Supports copy and download. Runs locally, no data leakage.
- [Git Cheatsheet](https://www.wcytcn.com/en/tools/git-cheatsheet): Free online Git cheat sheet covering everyday commands for basics, branching, remotes, undoing changes, and stashing. Keyword search and category browsing included. Runs locally for instant lookup.
- [Docker Cheatsheet](https://www.wcytcn.com/en/tools/docker-cheatsheet): Free online Docker cheat sheet covering image management, container operations, networking, volumes, and Compose commands. Keyword search and category browsing included. Runs locally for instant lookup.
- [Linux Commands Cheatsheet](https://www.wcytcn.com/en/tools/linux-cheatsheet): Free online Linux command cheat sheet covering file operations, text processing, process management, network troubleshooting, and permissions. Keyword search and category browsing. Runs locally.
- [SQL Cheatsheet](https://www.wcytcn.com/en/tools/sql-cheatsheet): Free online SQL cheat sheet covering queries, aggregations, joins, subqueries, window functions, and date handling, with runnable examples. Keyword search and category browsing. Runs locally.
- [Regex Cheatsheet](https://www.wcytcn.com/en/tools/regex-cheatsheet): Free online regex cheat sheet covering metacharacters, quantifiers, groups, lookahead assertions, and common patterns, with examples and explanations. Keyword search and category browsing. Runs locally.

### Encoding Tools (13)

- [Base64 Encoder/Decoder](https://www.wcytcn.com/en/tools/base64-decoder): Free online Base64 encoder and decoder with full Unicode-safe encoding support for Chinese and Emoji. All processing runs locally in your browser, no registration required.
- [URL Encoder/Decoder](https://www.wcytcn.com/en/tools/url-encoder): Free online URL encoder and decoder supporting both encodeURIComponent and full URL encoding. All data is processed locally in your browser, safe and private.
- [JWT Decoder](https://www.wcytcn.com/en/tools/jwt-decoder): Free online JWT decoder with HS256 signature verification. View Header, Payload, and Signature segments. Token is decoded locally in your browser, never sent to any server.
- [Regex Tester](https://www.wcytcn.com/en/tools/regex-tester): Free online regex tester with support for g/i/m/s flags. Real-time match highlighting for fast debugging. Runs entirely locally in your browser, no registration required.
- [UUID Generator](https://www.wcytcn.com/en/tools/uuid-generator): Free online unique ID generator supporting UUID v4, NanoID, and ULID. Powered by crypto.getRandomValues for true randomness. All IDs are generated locally in your browser.
- [HTML Entity Encoder/Decoder](https://www.wcytcn.com/en/tools/html-entity-encoder): Free online HTML entity encoder and decoder. Convert special characters like angle brackets and ampersands to HTML entities or decode them back. Runs locally, no registration.
- [CSV JSON Converter](https://www.wcytcn.com/en/tools/csv-json-converter): Free online CSV and JSON converter with auto header detection and type inference. Convert CSV to JSON array or JSON to CSV table. Runs locally in browser.
- [Image to Base64 Converter](https://www.wcytcn.com/en/tools/image-to-base64): Free online image to Base64 converter. Drag and drop, paste, or upload an image to get a Base64 Data URI. Perfect for inline images and CSS, runs locally.
- [Image Compressor](https://www.wcytcn.com/en/tools/image-compressor): Free online image compressor supporting JPEG, PNG, WebP compression and conversion. Custom quality and dimensions with real-time preview, runs locally.
- [Base64 to Image Online Tool](https://www.wcytcn.com/en/tools/base64-to-image): Free Base64 to image converter with auto MIME detection. Real-time preview and download support, decoded locally in your browser, never uploaded.
- [JWT Token Generator](https://www.wcytcn.com/en/tools/jwt-generator): Free JWT generator supporting HS256, RS256, and other signing algorithms. Custom Header and Payload, signed locally in your browser, never uploaded.
- [Unicode Encoder/Decoder](https://www.wcytcn.com/en/tools/unicode-encoder-decoder): Free Unicode encoder and decoder supporting \uXXXX, U+ code points, HTML entities, and UTF-8 bytes. Solves i18n encoding issues, runs locally.
- [Base32 / Base58 Encoder](https://www.wcytcn.com/en/tools/base32-base58-encoder): Free Base32 and Base58 encoder/decoder. Removes easily confused characters, ideal for blockchain addresses and short links, runs locally.

### Advanced Encoding Tools (3)

- [HTML Entity Encoder Enhanced](https://www.wcytcn.com/en/tools/html-entity-enhanced): Free online HTML entity encoder/decoder with 244 built-in named entities. Convert between decimal, hexadecimal, and named entities with multiple encode/decode modes, runs locally.
- [Base64 Batch Processor](https://www.wcytcn.com/en/tools/base64-batch): Free online Base64 batch processor with multi-line encode/decode, URL Safe variant, and original text reference. Greatly improves batch processing efficiency. Runs locally, no registration required.
- [Data URI Generator](https://www.wcytcn.com/en/tools/data-uri-generator): Free online Data URI generator tool supporting file and text to data: protocol URL conversion with both Base64 and URL encoding methods. Auto-detects MIME type, processed locally in browser with no uploads.

### Crypto & Hashing Tools (7)

- [SHA256 Hash Generator](https://www.wcytcn.com/en/tools/sha256-hash-generator): Free online hash calculator supporting SHA-1, SHA-256, SHA-384, and SHA-512. Powered by Web Crypto API for secure local computation. Data never leaves your browser, no registration.
- [AES Encrypt/Decrypt](https://www.wcytcn.com/en/tools/aes-encrypt-decrypt): Free online AES-GCM encryption and decryption tool with PBKDF2 256-bit key derivation. Processed locally in your browser. Ciphertext and password never sent to any server.
- [MD5 Hash Generator](https://www.wcytcn.com/en/tools/md5-hash-generator): Free online MD5 hash generator. Enter text to instantly get a 32-character MD5 hash value. Computed locally in your browser, data never sent to any server, no registration.
- [Bcrypt Password Hash](https://www.wcytcn.com/en/tools/bcrypt-hash): Free bcrypt hash generator designed for password storage with built-in salt and adjustable cost factor. Computed locally in your browser, never uploaded.
- [Certificate Decoder](https://www.wcytcn.com/en/tools/certificate-decoder): Free X.509 certificate decoder supporting PEM and DER formats. Parses subject, issuer, validity, and SAN. Certificates are never uploaded.
- [RSA Key Generator & Encrypt/Decrypt](https://www.wcytcn.com/en/tools/rsa-encrypt-decrypt): Free RSA encrypt/decrypt tool supporting 1024, 2048, and 4096-bit key generation. Powered by Web Crypto API, runs locally in your browser.
- [Hash Verifier](https://www.wcytcn.com/en/tools/hash-verifier): Free hash verifier supporting MD5, SHA-1, SHA-256, and SHA-512. Compute file hashes locally and compare checksums, data never leaves your browser.

### Security Tools (4)

- [Password Strength Checker](https://www.wcytcn.com/en/tools/password-strength-checker): Free online password strength checker with 9 weighted checks plus length bonus scoring, crack time estimation, and improvement suggestions. Evaluation runs locally in your browser, passwords never uploaded.
- [PGP Encrypt/Decrypt Tool](https://www.wcytcn.com/en/tools/pgp-tool): Free online PGP-style encryption tool: RSA-2048 wraps a random AES-256-GCM session key. Powered by Web Crypto API, runs locally — keys never leave your device.
- [TOTP Generator](https://www.wcytcn.com/en/tools/totp-generator): Free online TOTP generator following RFC 6238, supporting SHA-1/SHA-256, 6/8 digit codes, and 30/60 second steps. Secrets are stored only in your browser.
- [HMAC Generator](https://www.wcytcn.com/en/tools/hmac-generator): Free online HMAC multi-algorithm generator supporting MD5, SHA-1, SHA-256, SHA-384, and SHA-512 with Hex and Base64 output formats. Computed locally in your browser, secret key never leaves your device.

### API Tools (2)

- [cURL to Code](https://www.wcytcn.com/en/tools/curl-to-code): Convert cURL commands to HTTP request code in multiple languages
- [API Tester](https://www.wcytcn.com/en/tools/api-tester): Free online HTTP API tester supporting GET, POST, PUT, DELETE, and PATCH. Custom Headers and Body, 30s timeout with cancel. A simplified Postman alternative, runs locally.

### Format Tools (1)

- [HTML Formatter](https://www.wcytcn.com/en/tools/html-formatter): Free online HTML formatter supporting beautify and minify, adjustable indent, keep comments and blank lines. Safely preserves script/style/pre content, runs locally in your browser.

## Blog Guides (latest)

- [JSON Troubleshooting Handbook: From Error Message to Fix (Symptom Index)](https://www.wcytcn.com/en/blog/json-troubleshooting-handbook): JSON errors that make no sense? This handbook organizes fixes by symptom — syntax errors, Unicode escaping, encoding mojibake, and Schema validation failures, with a diagnostic tree and a general debugging workflow.
- [Character Encoding Troubleshooting Handbook: Mojibake, URL Encoding, and Base64 Explained](https://www.wcytcn.com/en/blog/encoding-troubleshooting-handbook): Chinese turning into ??? or é”±? %E4%B8%AD unreadable? This handbook classifies by symptom — real mojibake, URL percent-encoding, Unicode escaping, and Base64 with Chinese, plus an encoding primer and a debugging workflow.
- [Subnetting / CIDR Explained: What Is 192.168.1.0/24 and How to Calculate](https://www.wcytcn.com/en/blog/subnet-cidr-explained): What does CIDR like 192.168.1.0/24 mean, how to get the subnet mask, how to compute usable hosts? Explains subnetting with intuitive examples, plus our CIDR / subnet calculator.
- [SHA256 vs MD5: What Is the Difference and Which to Use?](https://www.wcytcn.com/en/blog/sha256-vs-md5-difference): SHA256 vs MD5 difference, why MD5 is no longer safe, and which hash to use for file verification? Compares length, security, and use cases, with our SHA256/MD5 tools.
- [Regex Matches Nothing / Greedy .* Swallows Results — How to Fix](https://www.wcytcn.com/en/blog/regex-match-fails): Online regex test matches nothing, or greedy .* eats too much, or groups capture nothing? Explains greedy vs lazy, escaping special chars, and anchors — with a step-by-step debug using our regex tester.
- [How to Generate a QR Code with Logo and Custom Colors (Design Without Third Parties)](https://www.wcytcn.com/en/blog/qr-code-designer): Want a good-looking QR code—add a brand logo, change colors, round corners? Learn QR code design limits and step-by-step how to generate one locally without image-host dependencies.
- [Can MD5 Be "Decrypted"? What Is a Collision?](https://www.wcytcn.com/en/blog/md5-decrypt-collision): People say "MD5 decrypt" — can MD5 actually recover the original? What is a collision attack and why is it dangerous? Clears the misconceptions, with our MD5 / SHA256 tools.
- [JWT Decoded Shows "signature invalid" / Verification Failed — Is That Normal?](https://www.wcytcn.com/en/blog/jwt-signature-invalid): JWT decoded but shows signature invalid or verification failed? Learn the difference between decode and verify, why it fails, and when you should just read the payload vs. actually verify.
- [How to Convert JSON to Java Entity Class (with annotations and List nesting)](https://www.wcytcn.com/en/blog/json-to-java): Got JSON API data and want the matching Java POJO? Learn JSON-to-Java type mapping and common annotations, and step-by-step how to generate serializable classes locally.
- [How to Convert JSON to Go struct (with json tags and nested types)](https://www.wcytcn.com/en/blog/json-to-go): Have a JSON API response and want the matching Go struct? Learn the JSON-to-Go type mapping rules and step-by-step how to generate code with json tags locally.
- [JSON Schema Reports "required" Property Missing — How to Locate and Fix](https://www.wcytcn.com/en/blog/json-schema-required-error): JSON Schema validation says a required property is missing, or type mismatch? Explains required / additionalProperties / type pitfalls and how to locate the exact level with our validator.
- [JSON Shows Chinese as \uXXXX Escapes After Formatting — How to Get Readable Text Back](https://www.wcytcn.com/en/blog/json-chinese-unicode-escape): Why does formatted JSON turn Chinese into \uXXXX Unicode escapes, and how do you convert it back to readable text? Explains the cause and shows a one-click fix, all processed locally in your browser.
- [HTML Table to JSON: How to Preserve Rows, Columns and Structure](https://www.wcytcn.com/en/blog/html-table-to-json): Converting an HTML table from a web page to JSON — how to keep headers, handle merged cells and nested structure? Step-by-step with our HTML table to JSON tool.
- [How to Verify File or Text Hashes Match (SHA-256 Comparison for Integrity)](https://www.wcytcn.com/en/blog/hash-verifier): Downloaded a file—how do you know it wasn't tampered with? Learn how hash verification works and step-by-step how to compare SHA-256/MD5 locally to confirm integrity.
- [Excel to JSON: Dates Become Numbers / Chinese Garbled — Fix](https://www.wcytcn.com/en/blog/excel-to-json): When converting Excel to JSON, dates turn into numbers like 44927, Chinese is garbled, empty cells vanish? Explains Excel serial dates and encoding pitfalls, with our Excel to JSON tool.

## Other Formats

- [llms-zh.txt](https://www.wcytcn.com/llms-zh.txt): Chinese edition of this file (中文版)
- [llms-full.txt](https://www.wcytcn.com/llms-full.txt): complete FAQ content for every tool