# Developer Tools

> Developer utilities — converters, builders, and checkers.

11 tools in this category.

- [ENV / Shell / Docker Converter](https://www.teafun.cyou/tools/env-converter/) — Convert .env files to JSON, YAML, TOML, shell export, and Docker ENV instantly in your browser. Nothing is uploaded — all conversion is client-side.
- [Text Toolkit](https://www.teafun.cyou/tools/text-toolkit/) — Chain text operations — case conversion, cleanup, encoding, find/replace, regex — into a live pipeline. Select lines with the gutter to apply ops to only chosen lines. 100% client-side.
- [JSON Formatter & Validator](https://www.teafun.cyou/tools/json-formatter/) — Format, validate, and minify JSON instantly in your browser. Zero network requests — your data never leaves your device.
- [JWT Decoder](https://www.teafun.cyou/tools/jwt-decoder/) — Decode JWT headers and payloads locally in your browser. Inspect claims, expiry, issuer, and timestamps without sending tokens anywhere.
- [Base64 Encoder / Decoder](https://www.teafun.cyou/tools/base64-tool/) — Encode and decode Base64 locally in your browser. Supports text conversion, URL-safe Base64, and file-to-Base64 export.
- [Cron Expression Builder](https://www.teafun.cyou/tools/cron-builder/) — Build cron expressions visually for Unix, Quartz, AWS EventBridge, and GitHub Actions. Preview upcoming run times instantly in your browser.
- [Structured Data Converter](https://www.teafun.cyou/tools/yaml-json-toml/) — Convert YAML, JSON, and TOML locally in your browser with multi-document YAML support and anchor resolution.
- [HTTP Security Headers Checker](https://www.teafun.cyou/tools/http-headers-checker/) — Paste raw response headers or curl -I output to review common security headers locally, including CSP, HSTS, and COOP.
- [Log Formatter](https://www.teafun.cyou/tools/log-formatter/) — Paste JSON, nginx, Docker, syslog, or plain logs to normalize, filter by level, and inspect them locally in your browser.
- [Reading Time Estimator](https://www.teafun.cyou/tools/reading-time/) — Estimate reading and speaking time instantly. Paste any text to get word count, character count, reading time, and speaking time — CJK-aware.
- [Color Palette + WCAG Checker](https://www.teafun.cyou/tools/color-palette-wcag/) — Check contrast ratios, AA/AAA compliance, generate palette variants, and export CSS or Tailwind v4 color tokens locally.