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JSON Formatter & Validator
Paste any JSON — raw, minified, or broken — to format it with proper indentation or compress it to one line. Syntax errors show the exact line and column.
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Free Developer Tools — Eighteen Browser Utilities for Dev and QA Work
AT USE has eighteen developer utilities that run in the browser. No account, no upload limits for text tools, no file storage. The tools cover the tasks that pull you to a separate tab when you’d rather stay in your editor: formatting a JSON or XML response, decoding a JWT, converting JSON to YAML, diffing two config versions, converting Markdown to HTML, generating shareable code images, picking colors and copying HEX/RGB/HSL values.
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Developer Tools
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JSON to YAML Converter
Paste any JSON and get clean, indented YAML in one click. Validates JSON first — syntax errors show the exact position. Handles nested objects, arrays, and all scalar types. Nothing uploaded.
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JWT Decoder
Paste any JSON Web Token to read the header algorithm, payload claims, and expiry timestamps in plain text. Works without the signing key. Nothing is sent to a server.
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Text Diff
Paste two versions of any text block and get a line-by-line comparison: additions, deletions, unchanged lines. Useful for reviewing config changes, API responses, or any two text blocks that should match but don’t.
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Base64 Encoder / Decoder
Encode plain text to Base64 or decode Base64 back to the original. Handles standard and Base64url encoding. Covers HTTP Basic Auth credentials, data URIs, and JWT segment inspection.
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Binary Translator
Convert between decimal, binary, hexadecimal, and octal. Accepts a single value or a space-separated list. Useful for subnetting calculations, bitwise debugging, and verifying bit-field constants.
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Case Converter
Paste any text and get 12 case formats simultaneously: camelCase, snake_case, PascalCase, SCREAMING_SNAKE_CASE, kebab-case, Title Case, and six more. All outputs update in real time.
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Regex Tester
Write and test regular expressions against your own input. Supports flags (global, case-insensitive, multiline, dotall). Match positions and capture groups are highlighted inline.
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UUID Generator
Generate UUIDs in v1, v4, or v5 format. Single or bulk output. One-click copy. Useful for test fixtures, database seeds, and correlation IDs.
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Unix Timestamp Converter
Convert a Unix timestamp (seconds or milliseconds) to a human-readable date, or convert a date back to an epoch value. Shows UTC and local time. Useful when reading log files, API responses, and JWT expiry fields.
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URL Encoder / Decoder
Encode strings to percent-encoded URL format or decode percent-encoded strings back to readable text. Handles double-encoding detection. Covers query parameters, path segments, and OAuth state strings.
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Cron Expression Builder
Build cron expressions visually with a chip interface or paste any cron string to decode it into plain English. Preview the next 5 fire times in UTC or local time. Supports crontab, GitHub Actions, and Kubernetes.
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Number Base Converter
Convert integers between binary, decimal, hexadecimal, and octal simultaneously. Supports 8–64-bit widths, two’s complement mode, prefix display (0b/0x/0o), and nibble grouping for binary output.
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Markdown to HTML Converter
Paste Markdown and get rendered HTML instantly. Live preview plus raw HTML tab. Supports tables, task lists, fenced code blocks, and strikethrough. Copy to clipboard or download as a standalone .html file.
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HTML Entity Encoder / Decoder
Encode special characters — < > & " ' — to HTML entities, or decode entities back to plain text. Live conversion, copy output. 100% browser-based.
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Code to Image Converter
Paste any code snippet and export it as a shareable PNG or JPEG. Eight syntax-highlight themes, 40+ languages, adjustable padding and font size. 2× resolution output. No account.
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XML Formatter & Validator
Paste any XML to format it with consistent indentation or minify to one line. Parse errors show the exact line and column. Handles SOAP envelopes, Maven POMs, Spring configs, and Atom feeds. 100% in-browser.
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Color Picker
Pick any color and instantly get the HEX, RGB, and HSL values. One-click copy for each format. Type a hex code directly to convert it. Runs entirely in your browser.
Open toolEighteen tools for the full developer workflow
Built for developers, QA engineers, and anyone working regularly with APIs, tokens, or data formats.
Each tool does one job immediately: JSON Formatter formats or minifies JSON and reports errors by line. JSON to YAML Converter converts any valid JSON to clean, indented YAML — validates first, handles nested objects, arrays, and all scalar types. XML Formatter & Validator formats or minifies XML using the browser’s native DOMParser — reports parse errors with exact line and column. JWT Decoder reads token claims without the signing key. Text Diff compares two text blocks line by line. Base64 encodes and decodes in both standard and URL-safe modes. Binary Translator converts across decimal, binary, hex, and octal. Case Converter outputs 12 formats simultaneously. Regex Tester highlights matches and capture groups inline. UUID Generator produces v1, v4, or v5 UUIDs in single or bulk mode. Unix Timestamp Converter shows UTC and local time for any epoch value. URL Encoder / Decoder handles percent-encoding and detects double-encoding. Cron Expression Builder builds or decodes cron strings and previews the next five fire times. Number Base Converter converts between binary, decimal, hex, and octal with two’s complement and nibble-grouping support. Markdown to HTML converts CommonMark + GFM Markdown to HTML with live preview and a download option. HTML Entity Encoder / Decoder encodes special characters (< > & " ') to HTML entities and decodes entities back to plain text, all in the browser. Code to Image Converter turns any code snippet into a shareable PNG or JPEG — eight themes, 40+ languages, 2× resolution. Runs entirely in the browser. Color Picker shows the HEX, RGB, and HSL values for any color you pick or type, with one-click copy for each format. Everything runs in the browser.
A common API debugging flow: paste a raw response into JSON Formatter → pull out the Authorization header value and decode it with Base64 Encoder → paste the JWT payload into JWT Decoder to check expiry → compare two response versions in Text Diff → test a field extraction pattern in Regex Tester. All eighteen tools share the same interface layout, so switching takes two seconds.
All processing is either client-side (JWT Decoder, Base64, Binary Translator, Case Converter, Regex Tester, UUID Generator, URL Encoder, Cron Expression Builder, Number Base Converter, Markdown to HTML, HTML Entity Encoder, Code to Image, JSON to YAML, XML Formatter, Color Picker) or handled within the current server request (JSON Formatter, Text Diff, Unix Timestamp). Nothing is stored after you leave the page.
Working with an API response?
Start with JSON Formatter to validate the structure before reaching for any other tool.
JSON Formatter →Frequently asked questions
Are these developer tools free?
Yes. All eighteen tools are free to use with no account, no subscription, and no usage cap.
Do you store the text or data I enter?
No. Input text is processed client-side or in the current server request. Nothing is logged or retained after you leave the page.
Can I use these tools on a phone or tablet?
Yes. All eighteen tools work in mobile browsers. Text-input tools (JSON Formatter, JSON to YAML, XML Formatter, Case Converter, Base64 Encoder, Markdown to HTML) are particularly well suited to mobile workflows — paste from the clipboard, copy the result back.