Developer Tools
Practical utilities for JSON, encoding, URLs, and web development.
Explore 16 free developer tools, including Base64 Encode / Decode, Chmod Calculator, Cron Expression Explainer, CSV & JSON Converter, and more.
Choose the right tool
Choose a utility based on the format boundary you are debugging: structured data, encoded bytes, a token, or a configuration expression. Formatting improves readability, validation checks syntax, and decoding reveals a representation. None of those operations proves that the data is authentic or suitable for the application receiving it. Keep a copy of the original input so you can compare changes.
- JSON Formatter & Validator: Find malformed JSON and inspect a readable structure before changing its values.
- CSV & JSON Converter: Move tabular data between CSV and JSON while checking headers and field types.
- Base64 Encode / Decode: Translate Base64 text and inspect encoding issues; Base64 does not encrypt data.
- JWT Decoder: Inspect token claims while remembering that decoding does not verify a signature.
Showing all 16 tools.
Base64 Encode / Decode
PopularConvert plain text and Base64 in either direction.
Chmod Calculator
Convert Unix file permissions between octal and rwx notation.
Cron Expression Explainer
Understand each field in a five-field cron schedule.
CSV & JSON Converter
Convert structured CSV and JSON data in either direction.
SHA Hash Generator
Generate SHA-2 hashes for text and files locally.
IPv4 Subnet Calculator
Inspect IPv4 networks and CIDR ranges without sending addresses to an API.
JSON Formatter & Validator
PopularValidate JSON, pretty-print it, minify it, and inspect JSON paths.
JSON Lines Converter
Convert between JSON arrays and JSON Lines / NDJSON.
JSON Pointer Evaluator
Navigate JSON with standard slash-separated JSON Pointers.
JSON to TypeScript Generator
Infer TypeScript types from JSON sample data.
JWT Decoder
Inspect JWT header, payload, and time claims locally.
Number Base Converter
Convert integers between binary, octal, decimal, and hexadecimal.
Regex Tester
Test JavaScript regex patterns and inspect matches and capture groups.
Semantic Version Comparator
Compare SemVer versions and inspect prerelease precedence.
UTF-8 Byte Counter
Count UTF-8 bytes, Unicode code points, and UTF-16 code units.
XML Formatter & Validator
Validate and format XML locally in your browser.
Worked example: debug a JSON response
- Use a non-sensitive sample such as {"items":[{"id":1,"price":12.5}],"next":null}. Validate it as JSON first; comments and trailing commas are not part of standard JSON.
- Inspect the formatted result. Here items is an array, id and price are numbers, and next is null. A quoted price such as "12.5" would instead be a string.
- If you generate TypeScript from the sample, review optional fields and other possible responses. One example cannot establish the full API contract, and TypeScript types do not validate network data at runtime.
Common mistakes to avoid
- Valid JSON is not necessarily valid application data. Required fields, acceptable ranges, and permissions need separate checks.
- Use synthetic examples for debugging tokens and configuration. A decoded JWT can be readable even when its signature is invalid or its claims are untrusted.