Developer Tools — JSON, Regex, Hash, Diff & More
Format JSON, encode/decode data, test regex, generate hashes, decode JWTs, and more — all client-side. 100% free and private — everything runs directly in your browser, nothing is ever uploaded to a server.
All Developer Tools (18)
Essential Developer Tools
Web development involves a constant flow of structured data, encoded strings, and pattern matching. Debugging this data — inspecting what an API actually returned, verifying that an encoded value round-trips correctly, or confirming that a regular expression matches exactly the right substrings — is a routine part of the job. Having fast, reliable browser-based tools for these tasks removes the friction of switching to a terminal, installing a package, or writing throwaway scripts.
JSON (JavaScript Object Notation) is the lingua franca of modern web APIs. When an endpoint returns a response, it often arrives as a single minified string with no whitespace — efficient for transmission but completely unreadable for debugging. A JSON formatter parses the string, validates its structure, and re-serializes it with consistent indentation and syntax highlighting, making it trivial to inspect nested objects and arrays. Validation catches malformed JSON — missing commas, trailing commas, single-quoted strings — before it silently fails in production code.
Base64 encoding represents binary data using only the 64 printable ASCII characters A–Z, a–z, 0–9, +, and /. It is used wherever binary data needs to pass through a text-only channel: embedding images directly in HTML or CSS via data URLs, encoding binary payloads in JSON, transmitting authentication credentials in HTTP headers, and storing binary blobs in environment variables. Understanding Base64 is essential because the encoded form looks opaque — a string of seemingly random characters — and only by decoding it do you see the actual content.
URL encoding (also called percent-encoding) converts characters that are not safe inside a URL — such as spaces, ampersands, and non-ASCII unicode characters — into a % followed by two hex digits. Developers frequently need to construct or inspect URLs containing complex query strings, especially when working with search APIs, OAuth redirect parameters, or deeply nested query structures. Regular expression testing is equally critical: regex is a domain-specific language with a steep learning curve, and small differences in syntax — a greedy vs. lazy quantifier, the presence or absence of an anchor — can dramatically change which strings are matched. A live tester with real-time highlighting makes the iteration loop from hypothesis to verified pattern much faster.
Frequently Asked Questions
What does the JSON formatter do beyond adding whitespace?
Beyond pretty-printing, the formatter fully parses the input to validate that it is syntactically correct JSON. If the input contains common mistakes — a trailing comma after the last array element, single-quoted strings, or an unquoted key — the parser will report an error with the approximate line and position, so you can pinpoint the problem rather than hunting through a minified blob.
When would I need to decode a Base64 string?
Common scenarios include inspecting a JWT (JSON Web Token) — the header and payload sections are Base64url-encoded and decode to readable JSON — examining a data URL embedded in HTML or CSS, reviewing binary payloads in API responses, and decoding credentials stored in Kubernetes secrets or CI/CD environment variables, which are conventionally Base64-encoded.
How do I use the regex tester for JavaScript specifically?
The tester uses the JavaScript RegExp engine, so the syntax and flag semantics match what you would get when writing regex in a Node.js or browser application. Supported flags include g (global), i (case-insensitive), m (multiline), s (dotAll), and u (Unicode). Entering your pattern and test string gives you a real-time view of all matches and capture groups, which is faster than iterating with console.log.