Developer tools
JWT Decoder
Decode JWT headers and payloads locally without sending tokens to a server.
Open toolTool categories
Developer and API tools
Choose a focused tool for a single task or continue through a connected workflow without repeatedly copying the same content.
31active tools
Who it is for
Who it is for
Developer tools are for engineers and QA testers debugging APIs, inspecting tokens, testing regular expressions, formatting queries, and converting payloads between formats. Everything processes in the browser with no server round-trip.
What you can do here
What you can do here
- Format and validate JSON, SQL, and YAML
- Decode and inspect JWT tokens safely
- Test regular expressions with live examples
- Encode and decode Base64 and URL strings
- Generate UUIDs, hashes, and HMACs
- Inspect API responses, headers, and CORS setup
Featured tools
Featured tools
Developer tools
Regex Tester
Test regular expressions, inspect matches, capture groups, and replacements.
Open toolDeveloper tools
Base64 Encoder and Decoder
Encode text as Base64 or decode Base64 back to text.
Open toolDeveloper tools
URL Encoder and Decoder
Encode or decode URL components safely.
Open toolA practical connected workflow
A practical connected workflow
Start with raw input, clean or inspect it, convert the result, and download the final output.
- 1Add your input
- 2Choose the options
- 3Review the result
- 4Download
Built for repeat daily work
Every active tool includes a working interface, clear instructions, examples, privacy details, limitations, and direct links to related tasks.
Data processing noticeAll tools in this category
All tools in this category
Developer tools
API Response Inspector
Analyze JSON API responses for structure, nulls, repeated records, size, paths, and potential sensitive fields.
Open toolDeveloper tools
JSON to TypeScript Generator
Generate TypeScript interfaces from JSON with nested types, arrays, optional fields, and configurable naming.
Open toolDeveloper tools
SQL Formatter
Format SQL statements with readable indentation and keyword casing.
Open toolDeveloper tools
HTML Formatter
Format HTML markup with readable nesting and consistent indentation.
Open toolDeveloper tools
CSS Formatter
Beautify CSS rules and declarations for easier review.
Open toolDeveloper tools
JavaScript Formatter
Format JavaScript source code into a cleaner readable layout.
Open toolDeveloper tools
HTML Minifier
Reduce HTML size by removing safe whitespace and comments.
Open toolDeveloper tools
CSS Minifier
Compress CSS while preserving declarations and selectors.
Open toolDeveloper tools
JavaScript Minifier
Apply conservative JavaScript whitespace and comment reduction.
Open toolDeveloper tools
Regex Tester
Test regular expressions, inspect matches, capture groups, and replacements.
Open toolDeveloper tools
Cron Expression Generator
Build standard five-field cron expressions from clear scheduling controls.
Open toolDeveloper tools
Unix Timestamp Converter
Convert Unix timestamps to dates and dates back to timestamps.
Open toolDeveloper tools
JWT Decoder
Decode JWT headers and payloads locally without sending tokens to a server.
Open toolDeveloper tools
JWT Expiry Checker
Inspect JWT time claims and calculate expiration status.
Open toolDeveloper tools
UUID Generator
Generate one or many cryptographically strong UUID version 4 values.
Open toolDeveloper tools
Hash Generator
Create SHA-1, SHA-256, SHA-384, and SHA-512 hashes in the browser.
Open toolDeveloper tools
HMAC Generator
Generate an HMAC from a message, secret key, and selected algorithm.
Open toolDeveloper tools
URL Encoder and Decoder
Encode or decode URL components safely.
Open toolDeveloper tools
Base64 Encoder and Decoder
Encode text as Base64 or decode Base64 back to text.
Open toolDeveloper tools
HTML Entity Encoder and Decoder
Encode HTML-sensitive characters or decode entities to text.
Open toolDeveloper tools
Query String Parser
Parse query strings into readable JSON and rebuild them when needed.
Open toolDeveloper tools
HTTP Header Analyzer
Inspect pasted HTTP headers for security, caching, and content signals.
Open toolDeveloper tools
CORS Header Analyzer
Review CORS response headers and highlight risky configurations.
Open toolDeveloper tools
OpenAPI Validator
Validate OpenAPI JSON or YAML structure and inspect endpoints.
Open toolDeveloper tools
GraphQL Formatter
Format GraphQL queries, mutations, fragments, and variables.
Open toolDeveloper tools
Environment File Validator
Check .env syntax, duplicates, spacing, and potentially exposed secrets.
Open toolDeveloper tools
API Response Diff
Compare two JSON API responses and highlight structural changes.
Open toolDeveloper tools
XML Formatter
Format and validate XML documents with readable indentation.
Open toolDeveloper tools
YAML Formatter
Parse and reformat YAML into a consistent readable structure.
Open toolDeveloper tools
JSON to SQL Generator
Generate SQL table and INSERT statements from JSON records.
Open toolDeveloper tools
SQL Result to JSON
Convert SQL-style tabular or INSERT data into JSON records.
Open toolGuides and solutions
Guides and solutions
Go deeper with practical guides and step-by-step workflows built around these tools.
How to create strong passwords
A practical guide to creating strong passwords: length, randomness, passphrases, and how to store them safely.
Learn moreHow to generate and use UUIDs
A guide to UUIDs: what they are, when to use them as database keys and API IDs, and how to generate them correctly.
Learn moreHow to format SQL for readability
A guide to readable SQL: consistent casing, clause placement, indentation, and when to use the formatter.
Learn moreHow to convert JSON to TypeScript safely
A guide to generating TypeScript types from JSON: interfaces, unions, nullability, and keeping types in sync with APIs.
Learn moreHow to encode and decode Base64, and why it is not encryption
A guide to Base64: what the encoding does, when to use it, how to encode and decode locally, and why it adds no security.
Learn moreHow to check JWT expiry before using a token
A guide to reading the exp claim in JWT tokens, checking expiry locally, and handling tokens that are about to expire.
Learn moreHow to debug CORS errors in the browser
A guide to diagnosing CORS errors: reading the browser message, checking response headers, and fixing the server side.
Learn moreHow to test regular expressions with reliable examples
A practical regex testing method built around representative positive cases, negative cases, capture groups, replacement previews, and performance review.
Learn moreGenerate a hash for passwords and file checksums
Hashes verify integrity without revealing content: checksums confirm a file was not altered, and API signing relies on HMAC. The [hash generator](tool:hash-generator) produces MD5, SHA-1, SHA-256, and SHA-512 digests locally, and the [HMAC generator](tool:hmac-generator) adds keyed signing.
Open solutionTurn a JSON array into SQL INSERT statements
Seeding a database from an API export or a config file means turning JSON into INSERT statements. The [JSON to SQL tool](tool:json-to-sql) generates the statements locally with a table name and CREATE TABLE option, and the [CSV to SQL guide](guide:csv-to-sql-guide) covers the same workflow for spreadsheet data.
Open solutionShrink CSS and JavaScript to speed up your pages
Every kilobyte of CSS and JavaScript delays your page. Minification removes whitespace, comments, and formatting without changing behavior. The [CSS minifier](tool:css-minifier) and [JavaScript minifier](tool:javascript-minifier) work locally, and the [page speed guide](guide:reduce-image-size-for-website) covers the image side of the same problem.
Open solutionConvert XML to JSON for APIs and configs
APIs and configuration systems increasingly expect JSON, but legacy services still return XML. The [XML formatter](tool:xml-formatter) now converts XML to a JSON structure locally, mapping elements, attributes, and text in a predictable way.
Open solutionGenerate a strong password in seconds
Weak passwords are the reason accounts get compromised. The [password generator](tool:password-generator) creates random passwords with real entropy, lets you choose length and character sets, and never sends the result anywhere.
Open solutionGenerate UUIDs for database keys and API IDs
UUIDs give every record a unique identifier without a central counter. The [UUID generator](tool:uuid-generator) creates version 4 UUIDs locally, in bulk, and in the exact format your code expects.
Open solutionFormat SQL online in one paste
One-line SQL is impossible to review. The [SQL formatter](tool:sql-formatter) re-indents queries, aligns keywords, and applies consistent casing, so you can read and review them instantly, all locally.
Open solutionConvert JSON to TypeScript interfaces in one paste
Typing API responses by hand wastes time and drifts from the real shape. The [JSON to TypeScript tool](tool:json-to-typescript) generates interfaces from a JSON sample instantly, locally.
Open solutionEncode or decode Base64 text and files
Base64 turns binary data into safe ASCII text for APIs, data URIs, and email. The [Base64 encoder and decoder](tool:base64-encoder-decoder) handles both directions locally, including file uploads, so nothing leaves your browser.
Open solutionURL-encode a query string safely
Spaces, ampersands, and non-ASCII characters break URLs unless they are encoded. The [URL encoder and decoder](tool:url-encoder-decoder) converts any string into a safe percent-encoded form and decodes it back, all locally.
Open solutionCategory questions
Category questions
No. Core tools are available without registration.
Most tools in this category process content locally in your browser.
Yes. Save local drafts in the browser workspace.
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