Hash Generator
Generate MD5, SHA-1, SHA-256, and SHA-512 hashes instantly
Freedeveloperhashmd5
31 browser-based tools
Developer tools for code, data, and debugging
These developer tools handle the small, repeatable jobs that interrupt real engineering work: formatting payloads, validating syntax, decoding tokens, generating identifiers, and inspecting web metadata. Each utility opens directly in the browser and produces usable output without an account. Tool inputs are processed on your device, so private code and payloads are not uploaded to Toolk.
Tool inputs stay on your device. Page-view analytics never include tool input.
Browse developer tools
Featured starting points appear first, followed by the complete category in alphabetical order. Every card links to one canonical tool page with its own working interface, examples, limitations, sources, and related utilities.
JSON Formatter
Format, validate, and beautify JSON data with advanced error handling
Freedeveloperjsonformatter
JSON to YAML Converter
Bidirectional JSON ↔ YAML converter with custom serializer and YAML 1.2 subset parser tuned for real-world configs (Kubernetes, GitHub Actions, Docker Compose, Ansible). Inline error reporting and one-click direction toggle.
Freedeveloperjson to yamlyaml to json
JWT Decoder
Decode JSON Web Tokens to inspect header, payload, and claims with expiration check — 100% client-side
Freedeveloperjwtdecoder
Password Generator
Generate strong, secure passwords with custom options
Freedeveloperpasswordgenerator
Production Nginx Config Generator
Generate production Nginx configs for static HTML, Node.js, or Python apps with persistent security controls, copyable deployment commands, and optional Certbot HTTPS.
Freedevelopernginx configreverse proxy
Regex Tester
Test and debug regular expressions with live matching
Freedeveloperregextester
UUID Generator
Generate unique UUIDs (v1, v4, v5) for your applications
Freedeveloperuuidgenerator
AltCatch
Audit any page for missing alt text and broken images, then export clean Markdown reports
Freedeveloperaccessibilityalt-text
Cron Expression Builder
Write, parse, and validate any standard 5-field cron schedule with next-fire times and plain-English description
Freedevelopercronscheduler
CSS Beautifier
Format minified CSS into clean, readable code with proper indentation
Freedevelopercssbeautifier
CSS Minifier
Minify and compress CSS code to reduce file size
Freedevelopercssminifier
HMAC Generator
Compute HMAC signatures (SHA-1, SHA-256, SHA-384, SHA-512) via the Web Crypto API with hex, Base64, and Base64URL output. Used for JWT HS256, AWS Sig V4, GitHub webhooks, and API request signing.
Freedeveloperhmachmac sha256
HTML Formatter
Format and beautify HTML code with proper indentation
Freedeveloperhtmlformatter
HTML to JSX
Convert HTML to React JSX: 30+ attribute renames (class→className, for→htmlFor, event handlers to camelCase), inline styles to object syntax, void elements self-closed, HTML comments translated.
Freedeveloperhtml to jsxreact converter
HTTP Status Codes
Complete searchable reference for every HTTP status code (1xx-5xx) with plain-English descriptions, typical use cases, and RFC 9110 citations — including WebDAV, rate-limit, and captive-portal extensions
Freedeveloperhttp status codesrest api
JavaScript Minifier
Minify and compress JavaScript code for production
Freedeveloperjavascriptminifier
JSON Diff
Semantic JSON comparison — walk two JSON trees and emit path-indexed added / removed / changed records. Ignores whitespace and key order. Distinct from line-by-line text Diff Checker.
Freedeveloperjson diffjson compare
JSON Schema Generator
Generate JSON Schema (Draft 2020-12, 2019-09, or Draft-07) from any JSON example with inferred types, required fields, and detected string formats (email, uuid, date-time, uri, ipv4).
Freedeveloperjson schemadraft 2020-12
JSON to TypeScript
Generate clean TypeScript interfaces from any JSON with recursive nested types, array unions, and configurable style
Freedevelopertypescriptjson
LLM Token Counter
Estimate prompt tokens, API cost, and context use across current GPT-5.6, Claude, and Gemini models with dated links to official pricing sources
Freedevelopertoken countergpt tokens
Markdown to HTML
Convert Markdown to clean HTML with side-by-side rendered preview. Supports CommonMark essentials plus GFM strikethrough, fenced code, and tables. 100% client-side custom parser.
Freedevelopermarkdown to htmlmd converter
Meta Tag & OG Previewer
Paste HTML and see live Google SERP, X, Facebook, and LinkedIn previews with length checks and per-rule SEO validation
Freedeveloperseometa tags
Number Base Converter
Convert numbers between binary, octal, decimal, hexadecimal, and any base 2-36 with BigInt precision and two's complement support
Freedeveloperbinaryhex
Open Graph Tag Generator
Generate HTML <head> meta tags for Open Graph (Facebook/LinkedIn/Slack), Twitter Card, description, canonical, and theme-color from a simple form. Character-count guidance based on 2026 platform best practices.
Freedeveloperopen graphog tags
Password Strength Meter
Offline password strength tester with entropy math, breach-corpus check, pattern detection, and crack-time estimates
Freedeveloperpasswordsecurity
Random Number Generator
Cryptographically-strong random integers in any range with no modulo bias — up to 10,000 numbers, optional uniqueness and sort
Freedeveloperrandomrng
SQL Formatter
Format and beautify SQL queries with syntax highlighting
Freedevelopersqlformatter
URL Parser
Decompose any URL into protocol, host, port, path segments, query parameters (as a table), and hash using the native WHATWG URL parser. Decoded and raw values shown side-by-side.
Freedeveloperurl parserquery parameters
XML Formatter
Beautify or minify XML with native DOMParser validation. Works on SOAP envelopes, RSS feeds, sitemaps, Android string resources, SVG, and Office Open XML. 100% client-side.
Freedeveloperxml formatterxml beautifier
YAML Validator
Validate, format, and convert YAML with line-precise errors — ideal for GitHub Actions, Kubernetes, Docker Compose, and Ansible
Freedeveloperyamlvalidator
What can you do with these tools?
This category groups tools by the job they complete, not by a search-keyword variation. Choose the smallest utility that matches the input and output you need.
- Format and validate JSON, YAML, XML, SQL, HTML, CSS, and JavaScript.
- Inspect JWTs, URLs, HTTP status codes, hashes, and HMAC signatures.
- Generate UUIDs, JSON Schema, TypeScript types, and Open Graph tags.
- Debug regex, text differences, CSS specificity, and cron schedules.
Guides for this tool category
These guides explain the standards, formulas, and failure cases behind the working tools. Use them when the conversion result needs more context than a one-line output.
Developer Tools
Browser-Based Developer Tools for 20 Everyday Tasks
A practical map of 20 browser-based developer tools for formatting, conversion, debugging, security, CSS, and web metadata, with limits and source standards.
Read guideWeb Development
Complete Guide to JSON: Validation, Formatting, and Best Practices
How to validate and format JSON correctly: RFC 8259 syntax rules, common parser errors, schema checks, and formatting defaults that keep API diffs clean.
Read guideWeb Development
7 Common JSON Errors and How to Fix Them
The 7 JSON errors that break parsers every day — trailing commas, single quotes, unquoted keys, comments, bad brackets, wrong types — with the exact fix.
Read guideFrequently asked questions
Do Toolk developer tools upload code or API data?
No. The developer utilities process tool input in your browser. Toolk uses page-view analytics, but the code, payloads, secrets, and files entered into a tool are not included in that telemetry.
Which developer tool should I start with?
Start with the task in front of you. Use JSON Formatter for API payloads, Regex Tester for pattern debugging, JWT Decoder for token inspection, and Diff Checker for comparing text or code.
Can I use these tools without creating an account?
Yes. Every developer tool in the current catalogue opens without signup. Access and pricing are stated per tool; all tools currently listed in this category are free to use.
Last updated: . Category membership and tool counts come directly from the current Toolk catalogue.
Need a different tool?
Browse all 90 browser-based tools (90 currently marked free), or tell us what useful utility we should build next.