Smart Online Tools
Free online developer tools
Format, validate, compare, encode, and inspect code and data with browser-based developer utilities. Use these tools for quick checks on JSON, XML, YAML, HTML, CSS, JavaScript, URLs, tokens, and text without installing a desktop app.
Your input is processed on your device and is not sent to our server. Some tools load their formatter library from this website the first time you use them; the text you enter stays in your browser.
Browse the developer tools
Choose a tool for the file or value you are working with. Each page explains what it checks and where its limits are.
JSON Formatter
Format, minify, and validate JSON in your browser.
JSON Validator
Check JSON syntax and see parser errors before using a payload or config file.
JSON Visualizer
Explore JSON objects and arrays as a collapsible tree.
XML Formatter
Format XML markup with consistent indentation and readable nesting.
XML Validator
Check whether an XML document is well-formed.
YAML Formatter
Format YAML data with consistent indentation and line breaks.
HTML Beautifier
Indent HTML markup to make document structure easier to read.
CSS Beautifier
Format CSS rules and declarations with readable spacing.
JavaScript Beautifier
Format JavaScript with syntax-aware indentation and line breaks.
JavaScript Minifier
Compress and mangle JavaScript code in your browser.
CSS Minifier
Compress CSS by removing redundant syntax and whitespace.
URL Encoder
Percent-encode text for safe use as one URL component.
URL Decoder
Decode percent-encoded URL text into readable characters.
Base64 Encoder
Encode UTF-8 text as Base64.
Base64 Decoder
Decode Base64 text back into UTF-8 characters.
JWT Decoder
Decode a JSON Web Token header and payload for inspection.
Regex Tester
Test a regular expression against text and inspect matches and groups.
UUID Generator
Generate one or more random version 4 UUIDs.
SHA-256 Hash Generator
Generate a SHA-256 digest from text using Web Crypto.
MD5 Hash Generator
Generate an MD5 digest for legacy compatibility checks.
Mermaid Diagram Maker
Render flowcharts and other diagrams from Mermaid text.
HTML CSS JavaScript Playground
Try HTML, CSS, and JavaScript in an isolated browser preview.
Format and validate data files
Use the JSON Formatter to indent compact API responses or configuration files, then use JSON Validator when you only need a syntax check. XML Formatter and XML Validator help inspect markup and confirm that tags are well-formed. YAML Formatter is useful for readable settings files, where indentation affects the parsed structure.
A parser can confirm syntax, but a valid document may still be rejected by an API or application. Check schemas, required fields, and project-specific rules separately. Keep the original file before replacing configuration that a deployment depends on.
Make source code easier to review or ship
HTML, CSS, and JavaScript Beautifiers add consistent indentation to compact code. JavaScript and CSS Minifiers create compact output for distribution. Minification is a build step, not a substitute for keeping readable source: test the output in your project, especially when code depends on names, source maps, or browser-specific behavior.
The tools process pasted text in your browser. They do not run JavaScript that you paste into the formatter or minifier. Review any output before using it in production.
Encode, inspect, and compare text
URL Encoder and URL Decoder work on one URL component, such as a query value, rather than an entire URL. Base64 Encode and Base64 Decode convert UTF-8 text; Base64 is reversible encoding and does not hide secrets. JWT Decoder displays a token header and payload but does not verify its signature or claims.
Regex Tester checks JavaScript regular expressions against sample text. Text Diff Checker marks changed lines. UUID Generator creates random identifiers for development, and SHA-256 and MD5 tools produce text digests for comparison or compatibility work.
Visualize data and try web code
JSON Visualizer turns nested objects and arrays into a collapsible tree, which is handy when scanning a large API response. Mermaid Diagram Maker renders flowcharts and supported diagrams from text definitions. The HTML CSS JavaScript Playground runs examples in a restricted preview frame, so you can quickly check a small snippet without setting up a project.
The playground blocks network access and navigation and is not a complete development environment. Mermaid diagrams use Mermaid syntax rather than freeform drawing. Check diagrams and code in the application where you plan to use them.
Choose hashes carefully
SHA-256 is a general-purpose cryptographic hash, but it is not encryption and should not be used alone to store passwords. MD5 is included only for older systems and non-security compatibility checks; it is broken for security-sensitive use. For password storage, use a dedicated password hashing scheme such as Argon2id, scrypt, or bcrypt on the system that handles authentication.
Frequently asked questions
Are my code snippets uploaded?
No. The utilities run in your browser. Formatter packages may be downloaded as part of the page, but the text you enter is processed locally.
Does valid JSON mean an API will accept it?
No. JSON validation checks syntax only. The API may require particular fields, types, authentication, or business rules.
Does the JWT Decoder verify a token?
No. It decodes readable claims for inspection. Your application must validate the signature and check issuer, audience, expiry, and other requirements.
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