Free Online Developer Tools

What you can do with these developer tools

The collection covers the small, repetitive jobs that interrupt real development work. Instead of installing an extension or writing a throwaway script, open a tool, paste your input and copy the result.

• JSON Formatter: pretty-print, minify and validate JSON, and see where parsing fails.
• CSV to JSON: turn spreadsheet exports into JSON ready for an API call or a test fixture.
• Base64 Encoder: encode text to Base64 or decode it back.
• URL Encoder: percent-encode query values or decode an encoded link.
• Hash Generator: create hash digests of text for checksums and comparisons.
• UUID Generator: generate random UUIDs for database keys and test data.
• JWT Decoder: read the header and payload of a JSON Web Token.
• Regex Tester: try a regular expression against sample text and see every match.
• Timestamp Converter: convert Unix timestamps to readable dates and back.
• HTML Entities: escape or unescape special characters for HTML.
• CSS Minifier: remove whitespace and comments to shrink a stylesheet.
• Color Converter: convert colours between HEX, RGB and HSL.

Why use browser-based developer tools?

Many online developer tools send whatever you paste to a server. That is a real risk when the input is an access token, a customer record or an internal config file. These developer tools run in your browser, so the data you paste is processed on your device instead of being uploaded.

They also load quickly, work on a phone or a locked-down work laptop, and need no account. Bookmark the ones you use most and they stay one click away.

How to use the developer tools

1. Pick a tool from the grid above, or search for it by name.
2. Paste or type your input.
3. Choose an option if the tool has one, such as encode or decode.
4. Copy the output, or download it where a download button is offered.

Developer tools for common tasks

Debugging an API response

Paste the raw response into the JSON Formatter to make it readable and to catch syntax errors such as a trailing comma. If the response includes a token, open it in the JWT Decoder to check its claims and expiry time.

Preparing data for a request

Use the URL Encoder for query string values, Base64 for text that must survive transport unchanged, and CSV to JSON when your test data starts life in a spreadsheet.

Quick front-end fixes

The CSS Minifier and HTML Entities tool handle small front-end jobs, and the Color Converter turns a designer’s HEX value into the RGB or HSL format your stylesheet needs.

Good to know before you use these developer tools

The JSON tools follow the format defined in RFC 8259, the JSON standard, so input that passes validation here should parse in any standard JSON library.

A JWT is signed, not encrypted. The JWT Decoder shows what a token contains, but it does not verify the signature, so never treat a decoded token as trusted until your server has checked it.

Base64 is an encoding, not encryption. Anyone can decode it, so do not use it to hide passwords or secrets.