URL Encode/Decode
Encode and decode URLs with percent-encoding support — fix broken query strings and API parameters instantly.
Developer Tools36 live toolsFree onlineNo sign-up
Free Developer Tools Online — No Sign-Up Required
Format code, validate data structures, convert formats, and debug developer input — all browser-native.
Every modern developer workflow involves at least one data-transformation step: formatting raw JSON from an API, decoding a JWT to inspect its claims, converting binary payloads to Base64, or testing a regex before shipping it to production. These tasks are repetitive, context-switching away from your editor is costly, and spinning up a local script just to check one value is overkill. Our free developer tools online run entirely in your browser — zero install, zero account, zero data sent to any server. Paste your input, get your output instantly. The full collection covers JSON formatting and validation, SQL beautification, regex testing with group highlighting, Base64 encoding and decoding, JWT inspection, UUID generation, URL encoding, cron expression parsing, bcrypt hashing, SHA-256 checksums, CSS minification, and more. Each tool opens in seconds and preserves your privacy because nothing ever leaves your machine.
JSON Formatter & Validator
Format, validate, and minify JSON with error highlighting — instantly beautify messy JSON responses.
HTML/XML Escape
Convert special characters to and from HTML entities — prevent XSS and fix broken markup instantly.
CSS Minifier/Formatter
Minify or beautify CSS code for production optimization or readable development — instant browser-side processing.
JavaScript Minifier/Formatter
Minify or beautify JavaScript code for production builds or debugging — reduce JS bundle size instantly.
SQL Formatter
Format and beautify SQL queries for better readability — clean up messy SELECT statements and JOIN chains.
YAML to JSON Converter
Convert between YAML and JSON formats instantly — essential for CI/CD, Kubernetes, and API config workflows.
CSV to JSON Converter
Convert CSV data to JSON and vice versa with ease — perfect for data import/export and API payload preparation.
UUID Generator
Generate UUIDs (v4) in bulk with instant copy and export — unique identifiers for databases and APIs.
AI Diagram Generator
Generate visual diagrams and flowcharts from prompts with a browser-native AI workspace.
UML Diagram Generator AI
Create UML class, sequence, use-case, and ER diagrams with live preview and export-ready output.
AI Agent Code Generator
Describe any task and get a complete AI agent with working code — build automation scripts, bots, and pipelines instantly.
Pomodoro Timer — Free Online Focus Timer
Stay focused with the Pomodoro Technique. 25-minute work sessions, 5-minute breaks, and 15-minute long breaks. Free online timer with sound alerts and session tracking.
AI Page Builder Agent
Generate complete, professional HTML pages from plain-text descriptions. Build landing pages, portfolios, dashboards, SaaS pages, and e-commerce sites with live preview, HTML export, Three.js 3D, Chart.js, and GSAP animations. Free, no account required.
Markdown to HTML Converter
Render markdown into clean sanitized HTML with a live preview — convert .md files to web-ready markup.
HTML to Markdown Converter
Convert raw HTML into clean readable markdown syntax — useful for blog migration and content portability.
XML Formatter & Validator
Pretty-print XML and flag malformed markup in your browser — format RSS, SOAP, and config XML files.
JSON to XML Converter
Transform JSON objects into formatted XML markup — convert API payloads to XML for SOAP and legacy integrations.
SQL to JSON Converter
Turn SQL INSERT statements into JSON data structures — useful for data migration and API payload generation.
Pretty Log Formatter
Clean up JSON logs, key-value lines, and stack traces for readability — debug server logs instantly.
Base64 Image Encoder
Convert uploaded images directly into Base64 strings — embed images inline in emails, HTML, or CSS.
Data URI Generator
Generate inline data URIs from uploaded files and text assets — eliminate external HTTP requests for small assets.
Environment Variables Parser
Parse .env file content into structured JSON and key/value tables — debug dotenv configs instantly.
Cron Expression Parser
Validate cron schedules and preview upcoming run times — debug cron jobs and scheduled task expressions.
Class Diagram Maker
Draft Mermaid-compatible UML class diagrams with a browser-based editor — visualize OOP architecture.
ER Diagram Maker
Create entity-relationship diagrams with schema notes and Mermaid output — design database schemas visually.
Flowchart Maker
Build process diagrams and flowcharts from Mermaid-style syntax — visualize workflows and logic instantly.
Sequence Diagram Maker
Visualize API and system interactions with Mermaid-compatible sequence diagrams — document microservices clearly.
AI Page Builder Agent
Generate professional landing pages, portfolios, dashboards, and more from a text description. Live preview, HTML export, and optional Three.js 3D, Chart.js, and GSAP animations — free, no account needed.
Query String Parser
Parse URLs and query strings into readable key-value parameters — debug API requests and redirects instantly.
Regex Escape Helper
Escape plain text safely for regular-expression literals — convert strings to regex-safe patterns.
JSON Path Finder
Search nested JSON objects and return matching paths for keys and values — JSONPath query tool.
Code Explainer
Paste any code snippet and get an instant plain-English explanation. Supports Python, JavaScript, TypeScript, Java, C++, Go, Rust, SQL, and 20+ languages with beginner-to-expert depth levels.
Error Message Solver
Paste any error log or stack trace and get instant root cause analysis with step-by-step fix instructions. Supports Python, JavaScript, Java, Node.js, React, and 20+ frameworks.
Code Converter
Convert code between 15+ programming languages with idiomatic AI output. Python to JavaScript, Java to C#, TypeScript to Python, SQL dialect conversion, and more — no login required.
JSON Schema Builder & Validator
Generate JSON Schema from sample payloads, validate example objects, and inspect required fields or type mismatches. It is useful when teams need portable contracts without spinning up a backend.
What can you do with free developer tools tools?
API development and debugging
Inspect JWT tokens from your auth provider, format raw JSON responses, decode Base64 payloads, and validate URL query strings — all without leaving your browser. When an API returns garbled output, paste it here to identify the encoding or format instantly.
Database and query work
Beautify sprawling SQL queries so you can read join chains and WHERE clauses at a glance. Cross-check values with a diff checker when comparing query results. Parse cron expressions to confirm your scheduled job will fire at the right intervals.
Security and credentials
Generate bcrypt hashes for password storage, compute SHA-256 checksums to verify file integrity, create strong UUIDs for primary keys, and decode JWT headers without sending sensitive tokens to a third-party server.
Front-end and DevOps automation
Minify CSS before bundling, encode special characters in URLs for query-string parameters, and validate regex patterns used in routing or input sanitisation. Cron expression parsing helps DevOps teams confirm CI schedules without needing a live cron daemon.
Developer Tools tools — frequently asked questions
Are these developer tools really free?
Yes — every tool on this page is permanently free to use. There is no trial period, no credit card, and no account required. The tools are funded by non-intrusive display advertising.
Do these tools send my data to a server?
No. Every tool on this page runs entirely in your browser using client-side JavaScript. Your input never leaves your machine. This is especially important for sensitive data like JWT tokens, passwords, and API keys.
Can I use these tools on mobile?
Yes. The tools are fully responsive and work on any modern smartphone or tablet browser. Touch input, paste, and copy actions all behave correctly on iOS and Android.
What is the most popular developer tool on this site?
JSON Formatter and Validator is consistently the most-used tool, followed by Base64 Encoder/Decoder, Regex Tester, and JWT Decoder. These four tools cover the majority of everyday developer data-inspection tasks.
Do you support keyboard shortcuts?
Most tools support standard OS shortcuts: Ctrl+A to select all, Ctrl+C to copy, and Ctrl+Z to undo. The site-wide search is accessible via Ctrl+K or the / key from any page.
How accurate is the regex tester?
The regex tester runs the native JavaScript RegExp engine, which is the same engine used in Node.js, Chrome, Firefox, and Safari. Patterns are evaluated in real time with full support for flags (g, i, m, s, u, y) and named capture groups.
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224+ browser-based tools across 13 categories — all free, no sign-up required.