Chain tools into pipelines
Stop copy-pasting between tools. Chain multiple tools into automated pipelines and run them with one click. Every step runs locally.
Decode JWT header, decode payload, check expiry and signature algorithm
Format JSON, extract all key paths, generate TypeScript type definitions
Generate SHA256 hash, Base64 encode, and extract a short fingerprint
Popular Tools
JSON Formatter
Online JSON formatter: beautify, minify, validate JSON with one click. Convert to TypeScript/Go/Java. Unicode-safe, supports Chinese and Emoji.
Base64 Encode/Decode
Online Base64 encoder and decoder with UTF-8 by default for Chinese and emoji, plus GBK / Latin-1 charset switching. All processing runs locally in your browser. No data sent to servers.
API Tester
Online API tester: GET/POST/PUT/DELETE/PATCH with custom Headers/Body, 30s timeout with cancel. Postman alternative.
JWT Decoder
Online JWT decoder with HS256 signature verification. Decode Header, Payload, Signature locally — hs256 online check without uploading your token.
Regex Tester
Online regex tester with support for g/i/m/s flags. Real-time match highlighting. Runs locally in your browser for fast regex debugging.
UUID Generator
Free online UUID generator: UUID v7 (time-sortable, index-friendly), v4, NanoID, and ULID in bulk, with version and timestamp parsing. Generated locally, never uploaded.
Code Formatter
Online code formatter powered by Prettier. Supports JavaScript, HTML, CSS, SQL formatting and safe minification. Protects string literals from being broken.
Password Generator
Online secure password generator: customizable length, uppercase, lowercase, numbers, symbols. Uses crypto.getRandomValues for true randomness. Generated locally, never stored.
Timestamp Converter
Online Unix timestamp converter: auto-detects seconds, milliseconds, microseconds. Supports Local, UTC, ISO 8601, and relative time. Essential for developers debugging timestamps.
URL Encode/Decode
Online URL encoder and decoder tool. Supports URI component encoding (encodeURIComponent) and full URL encoding. Processed locally in your browser.
Excel to CSV
Convert Excel (.xlsx/.xls) files to CSV format online. All processing is done locally in your browser.
MD5 Hash
Online MD5 hash generator: enter text to get a 32-character MD5 hash. Computed locally in browser, data never sent.
Latest Articles
Markdown to Word: Native Style Mapping and the Inline-Format Downgrade List
Turning a Markdown draft into a deliverable .docx: pandoc CLI vs in-browser local conversion, how headings/tables/code blocks map to native Word styles, which inline formats degrade to plain text, and why 'editable' beats 'looks right'.
px, rem, em: What Each CSS Unit Actually Answers, and How to Convert Without Surprises
The boundary between px, rem, and em (root-relative vs parent-relative), the px-to-rem formula and size table, the 62.5% trick's hidden costs, the Safari media-query rem trap, and browser minimum font size — with an online converter.
VIN Check Digit Explained: How to Calculate and Validate Position 9
How the VIN check digit works: 17-character structure (WMI/VDS/VIS), the transliteration and weight tables, a worked mod-11 example, the 30-year model-year code, and the four most common validation failures. Includes an online VIN validator.
Summary: ToolVault is a privacy-first, fully client-side developer toolkit: JSON formatter/converter, API tester, Base64/URL/JWT, regex tester, Hash/HMAC/AES, UUID/NanoID/ULID, Cron parser, CIDR calculator, code formatter, text diff and 189+ tools. All data stays in your browser.