Developer Tools
These are the small utilities that interrupt everyday work: a payload that will not parse, a cron line nobody can read, a timestamp in the wrong epoch, a YAML file that has to become JSON.
They matter more than most utilities for one specific reason. The data a developer pastes into them is often a real API response, a configuration file, or a token — the kind of thing that should not be sent to someone else's server to be formatted. Every tool in this group does its work in the page, with no request to any server.
Tools in Developer Tools
JSON Compare
Compare two JSON objects and highlight differences.
JSON Prettier
Format and validate raw JSON data.
Text Comparison
Compare two texts and highlight differences.
RegEx Tester
Test and visualize regular expressions.
Code Minifier
Minify JS, CSS, HTML and SQL code.
Base64 Converter
Encode and decode text or images.
JSON to Interface
Convert JSON objects to TypeScript interfaces.
Code Formatter
Beautify SQL, HTML, CSS code.
YAML ↔ JSON
Convert between YAML and JSON.
Markdown Editor
Write markdown with live preview.
Cron Parser
Explain cron expressions in English.
Curl to Fetch
Convert Curl commands to JS Fetch.
Epoch Converter
Convert Unix timestamps to dates.
Unit Converter
Convert across twelve measurement categories in one place.
Chmod Calculator
Visual Unix permission generator.
How these tools behave
- Formatting and minifying are text transformations, not compilers: they do not check that your code runs.
- The JSON tools follow the strict JSON specification, so trailing commas and single-quoted strings are errors, not warnings.
Frequently asked questions
Is it safe to paste a token or an API key here?
The input never leaves the page: there is no request carrying it anywhere. Two things are still worth knowing. Your operating system's clipboard history may retain what you copied, and any credential that has been pasted into a browser at all is usually worth rotating if it is production-critical.
Do these tools work offline?
Once the page has loaded, yes. They make no network calls of their own.
Guides
- Fixing invalid JSON: the eight errors that cause most failures — Trailing commas, single quotes, unescaped characters, NaN, duplicate keys and large integers — with the exact parser message each one produces.
- Writing regular expressions that do not hang — Greedy versus lazy quantifiers, the flags that matter, and the nested-repetition pattern that freezes a browser tab.
- Reading and writing cron expressions — Field order, the difference between */5 and 5, the day-of-month and day-of-week trap, and how to sanity-check a schedule.