Free Developer Tools
JSON, Base64, hashing, URL encoding, colours and number bases. All 14 run in your browser, so nothing you enter is uploaded.
JSON Formatter
Format, indent and minify JSON, with precise error positions when it will not parse.
JSON Validator
Check whether JSON is valid and get the exact line, column and reason when it is not.
Base64 Encoder & Decoder
Encode text to Base64 or decode Base64 back to text, with full Unicode support.
URL Encoder & Decoder
Percent-encode text for use in URLs, or decode an encoded URL back to readable text.
Hash Generator
Generate SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text using the Web Crypto API.
Color Converter
Convert colours between HEX, RGB, HSL and HSV, with a live preview and contrast check.
Number Base Converter
Convert whole numbers between binary, octal, decimal, hexadecimal and any base up to 36, with two's complement for negatives.
Binary to Text Converter
Convert binary to text and text to binary through UTF-8, with hex and decimal byte views and clear errors for invalid input.
JSON to YAML Converter
Convert JSON to YAML and YAML back to JSON, quoting values that YAML would otherwise misread.
JSON to CSV Converter
Turn a JSON array of objects into a CSV file that Excel and Google Sheets open, or CSV back into JSON.
cURL to Fetch Converter
Turn a curl command into JavaScript fetch() code, listing any option that has no fetch equivalent.
HTML to Markdown Converter
Convert HTML, or rich text pasted from Google Docs or Word, into clean Markdown with lists and tables.
IPYNB to PY Converter
Convert a Jupyter notebook (.ipynb) into a Python script, with markdown as comments and magics commented out.
KML to GPX Converter
Convert KML to GPX or GPX to KML, keeping waypoints, tracks, names, elevations and timestamps.
About these developer tools
Developer utilities for the data you handle every day: format and validate JSON, convert JSON to YAML or CSV, encode and decode Base64 and URLs, generate hashes, convert colours and number bases, turn cURL commands into fetch() code, and convert HTML, notebooks and GPS files.
They run entirely in the browser and treat your input as data — nothing is executed, nothing is sent — which matters when the JSON contains API keys or customer records.
Developer Tools — questions
Is it safe to paste API responses or tokens?
Nothing you paste leaves your device. Still, treat secrets with care: avoid pasting live production credentials into any web page you do not control.
Why does a tool refuse some input?
When input is outside what a tool can convert reliably — YAML anchors, a .kmz archive, an unsupported cURL flag — it says so rather than producing output that looks right but is not.