All Developer Tools Directory (100+ Free Utilities)

Browse the complete collection of 100+ free browser-based developer tools on DevToolAdda. Format, convert, validate, and debug with zero server data storage.

AI Prompt Tools

AI Prompt Generator

Generate structured, high-performance prompts for ChatGPT, Claude, Gemini, and Perplexity with customizable roles, constraints, and quality scoring.

AI Prompt Tools

AI Prompt Improver

Transform basic or underperforming prompts into clear, precise, production-grade instructions with before/after score analysis.

AI Prompt Tools

SEO Prompt Generator

Generate high-ranking SEO content prompts optimized for search intent, keyword placement, headings structure, and featured snippets.

AI Prompt Tools

Blog Post Prompt Generator

Create complete blog writing prompts with audience calibration, required headings, FAQs, AEO snippets, and GEO entity scaffolding.

AI Prompt Tools

AI Image Prompt Generator

Structure photorealistic and stylized image prompts for Midjourney, DALL-E 3, Stable Diffusion, and Imagen with lighting, camera, and negative constraints.

AI Prompt Tools

AEO Prompt Generator

Optimize content for AI Overviews, Perplexity, and voice search with answer-first formatting, clear definitions, and question-based headings.

AI Prompt Tools

GEO Prompt Generator

Structure content for Generative Engine Optimization (GEO) with entity taxonomies, verifiable data points, source citations, and zero fluff.

AI Prompt Tools

Social Media Prompt Generator

Craft viral hooks, carousel outlines, and engaging social posts for LinkedIn, X (Twitter), Instagram, Threads, and Facebook.

AI Prompt Tools

YouTube Prompt Generator

Generate high-retention YouTube scripts, 30-second hooks, clickable title ideas, video descriptions with timestamps, and Shorts scripts.

AI Prompt Tools

System Prompt Generator

Build robust, safe, and authoritative system prompts for custom GPTs, AI agents, developer copilots, and production chatbots.

JSON Tools

JSON Formatter

Format, beautify, and inspect JSON data instantly with customizable indentation.

JSON Tools

JSON Validator

Check whether your JSON string is valid according to RFC 8259 specs.

JSON Tools

JSON Minifier

Compress JSON data by removing unnecessary whitespace and line breaks.

JSON Tools

JSON Viewer

Interactive tree viewer to explore nested JSON objects, arrays, and keys.

JSON Tools

JSON to CSV Converter

Convert JSON arrays into flat CSV tabular data for Excel or Google Sheets.

JSON Tools

CSV to JSON Converter

Convert CSV spreadsheets into structured JSON arrays.

JSON Tools

JSON to YAML Converter

Transform JSON definitions into clean YAML configuration files.

JSON Tools

JSON Diff Checker

Compare two JSON objects side-by-side to highlight additions, deletions, and modifications.

Encoding & Decoding

Base64 Encoder

Encode plain text or binary strings into safe Base64 representation.

Encoding & Decoding

Base64 Decoder

Decode Base64 encoded strings back into plain readable text.

Encoding & Decoding

JWT Decoder

Decode and inspect JSON Web Token headers, payloads, signatures, and expiration status.

Encoding & Decoding

URL Encoder

Encode special query parameter characters into percent-encoded URL values.

Encoding & Decoding

URL Decoder

Decode percent-encoded URI strings back into standard readable text.

Encoding & Decoding

HTML Entity Encoder

Convert sensitive HTML characters like <, >, &, and " into HTML entities.

Encoding & Decoding

HTML Entity Decoder

Decode HTML entity strings (like &lt; or &amp;) into raw characters.

Encoding & Decoding

Hex String Converter

Convert text strings to hexadecimal byte values and vice versa.

Generators

UUID / GUID Generator

Generate cryptographically strong Version 4 UUIDs or bulk unique IDs.

Generators

Password Generator

Create strong, customizable passwords with entropy strength estimation.

Generators

Random String Generator

Generate custom alpha-numeric random keys, tokens, or alphanumeric strings.

Generators

QR Code Generator

Generate high-resolution QR codes for URLs, text, Wi-Fi networks, and contact details.

Generators

Hash Generator (MD5, SHA-256)

Compute MD5, SHA-1, SHA-256, and SHA-512 cryptographic hashes for text.

Generators

Lorem Ipsum Generator

Generate placeholder text by paragraphs, words, or sentences for UI mockups.

Generators

Mock Data JSON Generator

Generate mock JSON arrays of users, products, addresses, and timestamps for testing.

Web Tools

HTML Formatter & Beautifier

Indentation, cleanup, and markup formatting for raw HTML code.

Web Tools

CSS Formatter & Beautifier

Format, align rules, and structure unformatted CSS stylesheets.

Web Tools

JavaScript Formatter

Format, indent, and beautify messy JavaScript and TypeScript code.

Web Tools

Meta Tag Generator

Generate essential HTML meta tags for title, description, viewport, and keywords.

Web Tools

Open Graph Meta Generator

Generate og:title, og:image, and Twitter Card meta tags for rich social media sharing previews.

Web Tools

Robots.txt Generator

Create valid robots.txt rules to guide search engine crawlers across site paths.

CSS Tools

Color Converter (HEX, RGB, HSL)

Convert color codes between HEX, RGB, HSL, and HSV with live palette picker.

CSS Tools

PX to REM Converter

Convert CSS Pixel measurements to relative REM units based on base font size.

CSS Tools

CSS Gradient Generator

Create linear and radial CSS background gradients with custom color stops.

CSS Tools

CSS Box Shadow Generator

Visually design CSS box shadows with offset, blur, spread, color, and inset controls.

CSS Tools

CSS Flexbox Playground

Interactive visual tool to test flex-direction, justify-content, align-items, and flex-wrap rules.

Text Tools

Text Case Converter

Convert text to UPPERCASE, lowercase, Title Case, camelCase, kebab-case, snake_case, and PascalCase.

Text Tools

Word & Character Counter

Count words, characters, sentences, paragraphs, and estimated reading time.

Text Tools

URL Slug Generator

Convert headlines and titles into clean, SEO-friendly URL slugs.

Text Tools

Remove Duplicate Lines

Deduplicate list lines, trim whitespace, and sort output alphabetically.

Text Tools

Text Diff Checker

Compare two text blocks side-by-side to highlight added, modified, or removed lines.

Regex Tools

Regex Tester & Debugger

Test regular expression patterns against test strings with real-time match highlighting.

Code Tools

SQL Formatter & Beautifier

Format, beautify, and align SQL queries across MySQL, PostgreSQL, and SQLite syntax.

Conversion Tools

Unix Timestamp Converter

Convert Unix epoch timestamps (seconds & milliseconds) to human readable date-times and vice versa.

Conversion Tools

Number Base Converter

Convert numbers between Binary (Base 2), Octal (Base 8), Decimal (Base 10), and Hexadecimal (Base 16).

Code Tools

Markdown Live Previewer

Write Markdown on the left and see formatted HTML rendering in real-time on the right.

Git Tools

.gitignore File Generator

Generate .gitignore files tailored to Node, React, Python, macOS, VS Code, and Go environments.

Git Tools

Conventional Commit Builder

Construct clean, standardized Conventional Commit messages (feat, fix, docs, refactor, chore).

Image Tools

Image to Base64 Converter

Convert local image files into Base64 data URI strings for CSS and HTML embedding.

Image Tools

Base64 to Image Converter

Decode Base64 image data URIs back into downloadable PNG or JPG files.

Image Tools

Image Resizer & Compressor

Resize and compress image dimensions (width/height) using browser Canvas API.

Calculator Tools

Percentage Calculator

Calculate percentage values, percentage of total, and percentage differences with step-by-step formulas.

Calculator Tools

Percentage Increase Calculator

Calculate the percentage growth or increase from an initial value to a new value.

Calculator Tools

Percentage Decrease Calculator

Calculate the percentage reduction, drop, or decrease from an initial value to a new value.

Calculator Tools

Average Calculator

Calculate arithmetic mean, median, mode, range, sum, count, and standard deviation for any dataset.

Calculator Tools

Ratio Calculator

Simplify ratios to lowest terms, find greatest common divisors (GCD), and compute equivalent scaled ratios.

Calculator Tools

Proportion Calculator

Solve for missing values in proportional equations (A / B = C / D) using cross multiplication.

Calculator Tools

Discount Calculator

Calculate sale prices, total savings, and final costs after percentage discounts and optional sales tax.

Calculator Tools

Profit Margin Calculator

Calculate gross profit, profit margin percentage, and markup percentage from cost and revenue.

Calculator Tools

Markup Calculator

Calculate the optimal selling price, gross profit, and profit margin based on item cost and desired markup.

Calculator Tools

VAT Calculator

Calculate Value Added Tax (VAT), gross prices, and net prices in inclusive or exclusive modes.

Calculator Tools

GST Calculator

Calculate Goods and Services Tax (GST) with CGST, SGST, IGST breakdowns for inclusive and exclusive amounts.

Calculator Tools

Age Calculator

Calculate exact chronological age in years, months, days, weeks, hours, and find days until next birthday.

Calculator Tools

Date Difference Calculator

Calculate the exact number of days, weeks, months, years, and business days between two calendar dates.

Calculator Tools

Time Duration Calculator

Calculate elapsed time, hours, minutes, and decimal hours between two clock times.

Conversion Tools

Unit Converter

Unified multi-category unit converter for length, weight, temperature, speed, area, volume, and data storage.

Conversion Tools

Length Converter

Convert lengths and distances across millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles.

Conversion Tools

Weight Converter

Convert mass and weight between milligrams, grams, kilograms, metric tons, ounces, pounds, and stones.

Conversion Tools

Temperature Converter

Convert temperatures between Celsius (°C), Fahrenheit (°F), Kelvin (K), and Rankine (°R) with benchmark scales.

Conversion Tools

Speed Converter

Convert velocity and speed between km/h, mph, m/s, ft/s, knots, and Mach numbers.

Conversion Tools

Area Converter

Convert surface areas across square meters, square feet, square inches, square kilometers, acres, and hectares.

Conversion Tools

Volume Converter

Convert volume and fluid capacity between liters, milliliters, cubic meters, gallons, quarts, pints, and fluid ounces.

Conversion Tools

Data Storage Converter

Convert digital storage sizes across Bits, Bytes, KB, MB, GB, TB, PB (Decimal 1000) and KiB, MiB, GiB, TiB (Binary 1024).

Conversion Tools

Time Zone Converter

Convert times across global time zones (UTC, EST, PST, GMT, CET, IST, JST, AEST) with synchronized world clocks.

Conversion Tools

Binary Converter

Convert Binary (Base 2) to ASCII text, Decimal (Base 10), Hexadecimal (Base 16), and Octal (Base 8).

Security & Web Utilities

HTTP Header Analyzer

Inspect and evaluate HTTP response headers for security flaws, missing CORS policies, and caching headers.

Security & Web Utilities

CSP Header Generator

Generate Content-Security-Policy (CSP) headers with custom script, style, image, and font directives.

Security & Web Utilities

SRI Hash Generator

Generate Subresource Integrity (SRI) SHA-256, SHA-384, and SHA-512 hashes for secure CDN script and stylesheet tags.

Security & Web Utilities

Basic Auth Header Generator

Create standard Authorization: Basic headers by encoding username and password credentials to Base64.

Security & Web Utilities

Bearer Token Generator

Format Bearer Token authorization headers for JWT, OAuth 2.0, and REST API testing.

Security & Web Utilities

CORS Header Generator

Configure Cross-Origin Resource Sharing (CORS) headers for Express, Nginx, Apache, and Cloudflare.

Security & Web Utilities

Set-Cookie Header Builder

Build secure Set-Cookie headers with Secure, HttpOnly, SameSite, Max-Age, and Path flags.

Security & Web Utilities

Cache-Control Header Generator

Generate HTTP Cache-Control headers with max-age, s-maxage, immutable, no-cache, and stale-while-revalidate directives.

Security & Web Utilities

MIME Type Lookup

Search and inspect standard MIME types, file extensions, and Content-Type headers.

Security & Web Utilities

HTTP Status Code Reference

Browse, search, and understand HTTP response status codes (1xx, 2xx, 3xx, 4xx, 5xx) with RFC explanations.

Security & Web Utilities

Port Number Reference

Search common network and developer ports (HTTP, HTTPS, SSH, MySQL, PostgreSQL, Redis, MongoDB).

URL & Web Development

URL Parser & Inspector

Parse URLs into protocol, host, port, path, query parameters, and hash fragments with structured editing.

URL & Web Development

Domain & Hostname Extractor

Extract root domains, subdomains, hostnames, and TLDs from URLs or bulk link lists.

URL & Web Development

URL Query Parameter Builder

Build and edit URL query parameter strings with automatic encoding, sorting, and key-value management.

URL & Web Development

URL Cleaner & Normalizer

Clean URLs by stripping UTM marketing tags, tracking tokens, duplicate slashes, and click identifiers.

URL & Web Development

URL List Cleaner & Deduplicator

Deduplicate, validate, sort, and clean bulk lists of URLs with customizable protocol and trailing slash rules.

API Development Tools

cURL Command Parser

Parse cURL commands into structured HTTP requests, headers, methods, and JSON request bodies.

API Development Tools

cURL to Fetch Converter

Convert cURL commands to JavaScript Fetch API code snippets (ES6 async/await and TypeScript).

API Development Tools

cURL to Axios Converter

Convert cURL commands into Axios HTTP client requests with async/await and TypeScript types.

API Development Tools

API Mock Response Generator

Generate realistic mock REST API responses for users, products, orders, authentication, and paginated lists.

API Development Tools

API Error Response Generator

Generate standard API error payloads compliant with RFC 7807 (Problem Details for HTTP APIs).

Database Tools

SQL CREATE TABLE Generator

Design database tables and generate CREATE TABLE DDL statements for PostgreSQL, MySQL, SQLite, and SQL Server.

Database Tools

SQL ALTER TABLE Query Builder

Generate SQL ALTER TABLE commands to add, drop, rename, and modify columns and constraints.

Database Tools

SQL Index Generator

Generate CREATE INDEX, UNIQUE INDEX, and composite index statements with partial WHERE clauses.

Database Tools

SQL IN Clause List Generator

Convert raw lists of IDs, strings, or UUIDs into formatted, quoted, and comma-separated SQL IN (...) clauses.

Database Tools

SQL Bulk INSERT Values Generator

Transform CSV or tab-separated data into multi-row SQL INSERT INTO ... VALUES (...) statements.

Markdown & Documentation

Markdown Table Generator

Interactive visual spreadsheet editor for creating, editing, and aligning GitHub-flavored Markdown tables.

Markdown & Documentation

Markdown Table to JSON Converter

Convert Markdown tables into structured JSON arrays of objects with automatic type parsing.

Markdown & Documentation

Markdown Table of Contents (TOC) Generator

Generate clean Table of Contents anchor links from Markdown headers (# H1, ## H2, ### H3).

Markdown & Documentation

Markdown & Shields Badge Builder

Design custom Shields.io badges for GitHub READMEs, package versions, build status, and tech stacks.

Markdown & Documentation

Open Source License Generator

Generate standard open-source software license files (MIT, Apache 2.0, GPLv3, BSD, ISC, Unlicense).

HTML Tools

Open Graph & Social Card Previewer

Generate Open Graph meta tags and preview real-time card appearances on Facebook, Twitter, LinkedIn, and Discord.

HTML Tools

Twitter / X Card Meta Tag Generator

Build Twitter Card tags (summary, summary_large_image, app, player) for optimal sharing on X/Twitter.

HTML Tools

HTML Meta Tag Generator

Complete SEO and social meta tag builder including viewport, charset, canonical, robots, OG, and theme-color tags.

HTML Tools

FAQ Schema (JSON-LD) Generator

Generate Google-compliant FAQPage structured data JSON-LD schemas for rich snippets in search results.

Frontend & Responsive Development

Pixel to REM / EM Calculator

Convert Pixel (px) values to CSS REM and EM units with customizable root base font sizes (16px default).

Frontend & Responsive Development

Device Screen Resolution Reference

Comprehensive database of viewport widths, device pixel ratios (DPR), and CSS resolutions for iPhones, iPads, Android, and laptops.

Frontend & Responsive Development

Viewport & Breakpoint Dimension Helper

Calculate fluid viewport units (vw, vh, vmin, vmax, dvh) and view matching responsive media query breakpoints.

Testing & QA

Bulk UUID v4 Generator

Generate up to 1,000 cryptographically secure UUID v4 identifiers at once in plain text, JSON, or SQL formats.

Testing & QA

Test Credit Card Generator (Luhn-Compliant)

Generate mock credit card numbers for testing payment gateways (Stripe, PayPal, Braintree) with valid Luhn checksums.

AI Developer Tools

AI Function Calling Schema Generator

Build function calling tool definitions and JSON schemas for OpenAI GPT-4, Google Gemini, and Anthropic Claude.

AI Developer Tools

Structured Output JSON Schema Generator

Generate strict response_format JSON schemas for OpenAI Structured Outputs and Gemini responseSchema.

AI Developer Tools

Vector Embedding Chunk Splitter

Split text and Markdown documents into overlapping chunks for RAG pipelines, LangChain, LlamaIndex, and vector databases.

Data & Visualization Tools

Mermaid Flowchart Generator

Create Mermaid.js flowcharts and process diagrams with visual node connectors, direction controls, and live syntax generation.

Data & Visualization Tools

Mermaid Sequence Diagram Builder

Design actor-to-actor message flows, API interactions, and asynchronous sequence diagrams in Mermaid.js syntax.

Data & Visualization Tools

Mermaid ER Diagram Builder

Create Entity Relationship (ER) database diagrams in Mermaid syntax with cardinalities and entity attributes.

Data & Visualization Tools

Mermaid Gantt Chart Generator

Build project roadmaps, sprint schedules, and milestone Gantt charts using Mermaid.js syntax.

Data & Visualization Tools

GeoJSON Feature & Geometry Builder

Build valid GeoJSON FeatureCollection, Point, LineString, and Polygon objects with custom properties.

Data & Visualization Tools

Geographic Bounding Box Calculator

Calculate minimum/maximum bounding box (BBOX) coordinates [minLon, minLat, maxLon, maxLat] from coordinate lists.

Git & Developer Workflow

Git Commit Message Builder

Draft clear, structured Git commit messages following standard industry conventions and team guidelines.

Git & Developer Workflow

Conventional Commits Generator

Build standardized Conventional Commits (feat, fix, docs, refactor, test, chore, perf) with scopes and breaking changes.

Git & Developer Workflow

Git Alias Generator

Generate productive Git shortcut aliases for .gitconfig (status, checkout, pretty logs, branch pruning).

Git & Developer Workflow

Git Branch Name Generator

Format consistent Git branch names with prefixes (feature/, bugfix/, hotfix/, chore/) and sanitized kebab-casing.

Git & Developer Workflow

Crontab & Schedule Expression Generator

Generate, test, and explain Cron schedule expressions (Minute, Hour, Day of Month, Month, Day of Week) in plain English.

Git & Developer Workflow

Semantic Versioning (SemVer) Calculator

Calculate next Major, Minor, Patch, and Pre-release version numbers based on SemVer 2.0.0 rules.

CSS & Frontend Tools

CSS Glassmorphism Generator

Create frosted glass UI effects with customizable backdrop-filter blur, background opacity, borders, and shadows.

CSS & Frontend Tools

CSS Clamp & Fluid Typography Calculator

Generate responsive fluid typography and spacing using CSS clamp(min, preferred, max) without media queries.

CSS & Frontend Tools

CSS Aspect Ratio Calculator

Calculate aspect ratios (16:9, 4:3, 1:1, 21:9), dimensions, and modern CSS aspect-ratio properties.

CSS & Frontend Tools

CSS Specificity Calculator

Calculate and compare CSS selector specificity scores (Inline, IDs, Classes/Attributes/Pseudo-classes, Elements).

JSON & Data Tools

JSONPath Evaluator & Finder

Query and extract deep properties from complex JSON objects using JSONPath expressions ($..store.book[*].author).

JSON & Data Tools

JSON to JSON Schema Generator

Infer and generate JSON Schema (Draft-07, Draft 2020-12) from sample JSON payloads with type detection.

JSON & Data Tools

JSON Flatten & Unflatten Utility

Flatten deeply nested JSON objects into dot-notated key paths (user.address.city) and reconstruct unflattened JSON.

JSON & Data Tools

JSON Key Sorter

Alphabetically sort object keys recursively in JSON documents for clean diffing and deterministic serialization.

JSON & Data Tools

JSON String Escape / Unescape

Escape quotes, newlines, and backslashes in JSON strings for embedding in code, and unescape stringified JSON.

JSON & Data Tools

JSON to JSON Lines (NDJSON) Converter

Convert standard JSON arrays to newline-delimited JSON (JSON Lines / NDJSON / .jsonl) and vice versa.