Case Converter - UPPER/lower/Title/camelCase/snake_case

1. Pick a format in three steps

Live conversion makes A/B checks cheap: flip camel versus snake on the same string and see which form your linter or API already expects. Prefer converting one representative file before repository-wide find-and-replace.

1. Paste prose or an identifier into the input panel.
2. Click the target style — Title/upper/lower for copy; camel for script variables; Pascal for types and components; snake for many backends; kebab for URLs, CSS classes, and filenames; CONSTANT for enums and env-style names.
3. Copy the output. For bulk renames, commit first so a bad sweep is easy to revert.

2. How acronyms are split

Camel input is cut on case boundaries first; remaining all-caps runs are greedily matched against a common acronym table (HTTP, URL, ID, and similar). Unknown runs stay intact as a single token, which is safer than inventing wrong breaks — and why sample checks still matter before mass renames. Failure sample: an internal product code like XMLishFOO may not match the lexicon and should be reviewed by eye before you replace hundreds of call sites.

3. Consistency habits that reduce review noise

Mixed conventions in one module are a frequent review comment. Convert at the boundary (import adapter, OpenAPI rename) rather than halfway through a call stack. Document the chosen style in the same PR description that lands the rename.

• Keep one naming convention per language surface (API fields vs UI labels vs file names).
• Prefer kebab-case in public URLs — many crawlers treat hyphens as word breaks.
• Eyeball proper nouns and brand tokens the lexicon does not know.

4. Why round-trips are not guaranteed

The classic accident is convert-then-convert-back and expect identity. Multiple legal splits can exist even with an acronym table. Conclusion: sample-check before bulk work; treat important codebase renames as reviewable diffs, not one-click magic. Keep the original list of identifiers until the pull request merges.

5. Unicode and locale pitfalls

If you need locale-aware Title Case for human prose in a specific language, verify on a native sample — this page optimizes for programming identifiers and general English-style title casing, not every Unicode casing edge case.

• Identifier modes use ASCII-safe letter mapping so Turkish-style I/i surprises do not rewrite code identifiers unpredictably.
• CJK mixed with Latin splits on script boundaries: CJK segments stay as-is; Latin segments follow the target style.

6. Versus slugify

Use this page when the input is already an identifier and you only need style changes. Use slugify when a human title (spaces, punctuation, CJK) must become a URL or filename. Both can emit kebab-case, but their input assumptions differ. Batch API field renames and config-key migrations belong here; blog titles belong on slugify.

7. Acceptance before bulk replace

If any hard case looks wrong, fix the source spelling or rename manually — do not paper over it with a second mass pass.

1. Convert five known hard cases (acronyms, digits, CJK mix) and read them aloud.
2. Run the project linter or compiler on one converted file.
3. Only then expand to the full rename list, with git history as the rollback path.

8. Bulk rename playbook

Export the list of identifiers you intend to change. Convert five edge cases on this page and paste results beside the originals in a spreadsheet. If reviewers accept the mapping, generate the remaining rows the same way and apply renames with your IDE’s symbol rename where possible — text replace across strings and comments is riskier. Leave a short note in the PR: source style, target style, and any identifiers intentionally skipped because the acronym lexicon would mangle them. That note prevents a follow-up PR that “fixes” careful exceptions. When CI fails on an unexpected symbol, check whether a generated protobuf or GraphQL name was converted accidentally; restore those from vendor outputs rather than hand-editing forever. Database columns may be case-insensitive on one engine and case-sensitive on another. Renaming API fields without versioning breaks clients — prefer additive aliases during migration. When converting CONSTANT_CASE env keys, confirm deployment manifests and secret stores are updated in the same change window.

• Prefer symbol rename over naive text replace for code identifiers.
• Skip generated and vendored files explicitly.
• Record skipped tokens next to the PR checklist.