26 free tools · no sign-up · 100% client-side
Developer tools that run entirely in your browser.
Format and validate JSON, generate typed models in 14 languages, convert between YAML, XML, CSV and Excel, decode JWTs, hash text and test regex — instantly, with nothing uploaded.
Private by design
Your input never leaves your device. No uploads, no logs, no accounts.
Instant results
Output updates as you type, even for multi-megabyte documents.
Works offline
Once a page loads, processing needs no network connection.
JSON
Format, validate, repair, compare and explore JSON.
- JSON Formatter & ValidatorFormat, validate, minify, repair, sort keys and view JSON as a tree.
- JSON DiffCompare two JSON documents and list every change.
- JSON Schema GeneratorInfer a JSON Schema (2020-12 or draft-07) from sample data.
- JSON Escape / UnescapeEscape or unescape text for JSON strings.
Converters
Convert data formats and generate typed code from JSON.
- Data Format ConverterJSON ↔ YAML, XML, CSV, TOML, Excel, SQL and more.
API & HTTP
Work with cURL commands, headers, status codes and OpenAPI.
- cURL ConverterConvert cURL to fetch, Axios, Python, Go or PHP.
- HTTP Headers ParserExplain raw headers and spot missing security headers.
- HTTP Status CodesSearch every HTTP status code and what it means.
- JSON to OpenAPICreate an OpenAPI 3.1 spec from a sample response.
Encoding
Encode and decode Base64, URLs, HTML entities, Unicode and hex.
- Base64 Encode / DecodeEncode/decode Base64 with UTF-8 and URL-safe support.
- URL Encode / DecodePercent-encode or decode URLs and query strings.
- HTML Entity EncoderEscape or unescape HTML entities.
- Unicode Escape ConverterConvert text to and from \uXXXX escape sequences.
- Text ↔ Hex ConverterConvert text to hex bytes and back (UTF-8).
Security
Inspect JWTs and compute hashes locally.
- JWT DecoderRead JWT header and claims, check expiry.
- Hash GeneratorMD5, SHA-1/256/384/512 and HMAC in one place.
Text
Convert case, sort lines and remove duplicates.
- Case ConverterConvert to camelCase, snake_case, kebab-case and more.
- Remove Duplicate LinesDeduplicate lines while keeping their order.
- Sort LinesSort lines alphabetically, naturally or by length.
Date & Time
Convert timestamps and understand cron schedules.
- Unix Timestamp ConverterEpoch seconds/ms to dates in any time zone and back.
- Cron Expression ParserExplain cron schedules and preview next runs.
Utilities
UUIDs, regular expressions, colors and QR codes.
- UUID GeneratorGenerate UUID v4 or v7 in bulk.
- Regex TesterTest regex with match groups and replace preview.
- Color ConverterHEX ↔ RGB ↔ HSL ↔ CMYK with contrast check.
- QR Code GeneratorMake QR codes and download PNG or SVG.
Frequently asked questions
Are the DevTools tools really free?
Yes. Every tool is free to use without an account, usage limits or watermarks. The site is supported by non-intrusive advertising.
Is my data sent to a server?
No. Formatting, conversion, decoding and hashing all happen in JavaScript inside your browser. Nothing you paste is uploaded, logged or stored on our servers, which makes the tools safe for internal data, tokens and configuration files.
Do the tools work offline?
Once a tool page has loaded, processing doesn't need a network connection. The code editor is loaded from a CDN the first time you open a tool.
Can I use these tools at work?
Yes. Because data never leaves your device, they are suitable for most corporate environments. Always follow your organisation's policies for handling sensitive data.