Developer tools for frontend developers
Test patterns, inspect payloads and decode values without leaving the browser — quick, local utilities for everyday frontend work.
Run the JSON Cleanup workflow → Browse all tools →
Launch a tool
Tip: press 1–8 to open one- 1Regex TesterPattern builder with presets and live match highlighting.
- 2JSON FormatterValidate, pretty-print, minify with tree view and secret detection.
- 3URL ParserParse URL parts, edit query params in a grid, rebuild.
- 4Base64 Encode / DecodeEncode or decode plain text to Base64.
- 5Encoding SuiteBase64URL, Hex, Gzip / Deflate, Querystring conversions.
- 6JWT DecoderDecode JWTs locally and verify HMAC signatures with a supplied secret.
- 7String Escape / UnescapeEscape & unescape strings for JSON, JS, SQL, regex, HTML, and more.
- 8Unicode & Invisible Character InspectorDetect and clean invisible, zero-width, bidi, and look-alike characters.
Run a workflow right here
Runs locally — nothing is uploadedJSON Cleanup & Sort
Pretty-print and sort JSON keys for stable diffs.
json-formatterJSON → YAML Converter
Convert a JSON document into YAML for config files.
json-yamlEncoding Inspector
Base64-decode an opaque payload and pretty-print the result if it's JSON.
base64-tool → json-formatterTrack a checklist
Progress is saved on this deviceDaily tasks, guides & FAQ
Common daily tasks
- Build and test a regex with live matches
- Format and inspect a JSON API response
- Parse and decode URL query parameters
- Encode/decode Base64 and data URIs
- Decode a JWT from local storage
- Convert JSON to YAML for config
Recommended workflows
- JSON Cleanup Sort — pretty-print and sort JSON keys.
- JSON to YAML — convert JSON to YAML.
- Encoding Inspector — Base64-decode a payload and pretty-print JSON.
- JSON Fingerprint — hash a normalized JSON payload to compare.
Top tools
Regex Tester
Test regular expressions with live match highlighting, capture groups and replacement preview.
Test a regex →JSON Formatter
Pretty-print, validate and sort JSON keys — the fastest way to read an API response.
Format JSON →URL Parser
Decompose a URL into scheme, host, path and query params for easy inspection.
Parse a URL →Base64 Tool
Encode or decode Base64 strings and data URIs locally.
Encode/decode Base64 →Why browser-local matters for frontend developers
Frontend debugging often means inspecting API payloads and tokens that may contain session data or user info. Everything runs 100% in your browser — no analytics scripts, no cookies, no third-party requests. We count anonymous visits at the CDN edge only. That means you can inspect and decode values safely without them leaving the page.
FAQ
Do these tools upload my data?
No. Everything runs 100% in your browser — no analytics scripts, no cookies, no third-party requests. We count anonymous visits at the CDN edge only. Payloads and tokens never leave the page.
Can I test a regex with live highlighting?
Yes. The Regex Tester shows matches, capture groups and a replacement preview as you type, with common presets and JavaScript-flavor notes.
How do I decode a JWT from local storage?
Paste the token into the JWT Decoder to read its header and claims locally — useful when debugging auth state in the browser.
Can I decode a Base64 data URI or payload?
Yes. The Base64 Tool and Encoding Suite decode Base64 and data URIs and can pretty-print decoded JSON.
Related
- API developers — decode tokens, verify webhooks, debug responses.
- Data / QA engineers — compare exports and clean datasets.
- All tools — the full utility catalog.
- Parse URL query parameters online