Developer tools that work.

323 free utilities for code formatting, file conversion, calculations, AI assistance, and more. No signup, no upload, no tracking.

Popular: JSON formatter · Password generator · QR code · AI chat · Image compressor · Speed test

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6 tools

APCA Contrast Checker - WCAG 3 Lc Calculator

Free APCA contrast checker for WCAG 3. Get the Lc value, the minimum Lc your font size and weight need, the WCAG 2.1 ratio, and a passing color fix.

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PDF Compare - Free Online PDF Diff & Side-by-Side

Free PDF compare tool. Side-by-side visual diff with scroll sync, text-based diff with green/red highlights, page-by-page navigation, export PDF report. 100% private browser processing, no upload, no signup.

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Math Calculator - Polynomial, Matrix, Prime Factor & More

Free math calculator. 6 modes: polynomial factoring, prime factorization, GCF/LCM, matrix (det/inv), quadratic formula, sequence. Step-by-step. No signup.

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Free OG Image Generator - Social Card Creator 1200x630

Free OG image generator. 1200x630 Open Graph cards with multi-platform preview (Twitter, Facebook, LinkedIn, Slack). 6 templates, custom colors, fonts, logo upload. Download PNG and copy meta tags. No signup, 100% browser. AI cannot output exact OG dimensions + multi-platform safe area validation.

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TDEE Calculator - BMR, Macro, Protein, Water, 1RM

Free TDEE calculator. 6 modes in one: BMR (3 formulas), macro split (5 diets), protein target, water intake, and 1 rep max. kg/lb toggle. No signup.

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AI Essay Writer - Free Academic Essay Generator

Free AI essay writer for 9 types, 4 levels, 5 citation styles. Outline + thesis + draft modes, editable, downloadable. No signup, no word limit.

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CSS Box Shadow Generator - Live Preview

Free CSS box shadow generator. Multi-layer shadows, depth presets, inset toggle, live preview. Copy production-ready CSS. No signup, 100% browser-based.

CSS Filter Generator - Visual CSS Filter Builder

Free CSS filter generator. Visually create CSS filter effects for images and elements. Blur, brightness, contrast, grayscale, sepia, hue-rotate and more.…

CSS Flexbox Generator - Visual Flex Layout Builder

Free CSS flexbox generator with interactive visual builder. Create responsive flex layouts with direction, wrap, justify, align, gap. Copy CSS code.

CSS Formatter & Validator - Beautify & Minify CSS Online

Free online CSS formatter and validator. Beautify messy CSS, minify for production, fix syntax errors. Instant results, no signup required.

CSS Gradient Generator - Linear, Radial & Conic Gradients

Free CSS gradient generator. Create beautiful linear, radial, and conic CSS gradients with live preview, angle dial, and multiple color stops. Copy CSS code or export SVG. No signup, 100% free.

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CSS Grid Generator - Visual Layout Builder

Free CSS grid generator with drag-and-drop builder. Create responsive grid layouts, columns, rows, gaps. Copy production CSS.

CSS to Tailwind Converter - Free Online Tool

Free CSS to Tailwind converter. Convert CSS properties to Tailwind utility classes instantly. 100+ properties supported.

cURL to Code Converter - Python, Node, Go, PHP, C#

Convert curl commands to Python, Node, Go, PHP, or C# code. Deterministic parser, 100% in-browser, no upload, no signup, and free to use forever.

Date Calculator - Days Between Dates & Date Arithmetic

Free online date calculator. Calculate days between dates, add or subtract days/weeks/months/years from any date, and compute business days. 100% private…

Days Until Calculator - Countdown to Any Date

Free days until calculator. Countdown to any date: Christmas, birthday, holiday, or event. See how many days, hours, minutes left. No signup required.

Debt Payoff Calculator - Snowball & Avalanche Free

Free debt payoff calculator. Compare avalanche vs snowball, see your debt-free date, total interest, and month-by-month payoff plan. No signup.

DNS & WHOIS Lookup - Check Domain Records

Free DNS lookup and WHOIS checker. Query DNS records (A, AAAA, MX, NS, SOA, TXT) and domain registration info instantly. No signup required.

Dog Age Calculator - Dog Years to Human Years

Free dog age calculator. Convert dog years to human years with AVMA + UCSD formulas. Breed presets, life stages, chart. No signup, private.

Domain Age Checker - Free WHOIS Domain Age Lookup

Free domain age checker. Check how old any domain is, creation date, expiry date, registrar, and nameservers. Instant WHOIS lookup, no signup required. AI…

Drawing Board - Free Online Whiteboard & Sketch Pad

Free online drawing board and whiteboard. Sketch, draw shapes, add text, and save as PNG. No signup, no upload, 100% private browser-based canvas tool. AI…

Due Date Calculator - Pregnancy Due Date & Ovulation…

Free due date calculator. Calculate your pregnancy due date using LMP, conception date, or IVF transfer. Ovulation calculator & period predictor…

Email Authentication Checker - SPF DKIM DMARC Check Online

Free email authentication checker. Check SPF, DKIM, and DMARC DNS records for any domain. Fix email deliverability. AI cannot check real DNS records - we…

Email Verifier - Verify Email Addresses Instantly

Free email verifier. Check if email addresses are valid and can receive messages. Detect disposable emails and SMTP issues. No signup required.

Engagement Rate Calculator - Multi-Platform Social Media

Free engagement rate calculator. 6 platforms (IG/TikTok/YT/X/FB/LI), 3 formulas, 5 tier benchmarks, weighted engagement. No signup.

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Excel to PDF Converter - Free Online XLSX to PDF

Free online Excel to PDF converter. Convert XLSX and XLS files to PDF directly in your browser. Preserves tables, multiple sheets, and formatting. No…

Excel Viewer - Free Online XLSX Viewer & Converter

Free online Excel viewer and converter. View XLSX, XLS, CSV files without Excel. Convert to JSON, CSV format. 100% private browser processing, no upload…

EXIF Viewer - Read Photo Metadata & Remove GPS Location Free

Free online EXIF viewer. Read hidden photo metadata including GPS location, camera settings, date taken. Remove EXIF data before sharing. 100% private, no…

Face Age Estimator - How Old Do I Look? Free AI Age Detector

Free AI face age estimator. Detect how old you look in any photo or via live camera. 100% private browser processing, no upload, no signup. Multi-face, expressions & gender. AI cannot analyze real faces - we do.

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Fancy Text Generator - Cool Unicode Fonts and Stylish Text

Free fancy text generator. Convert plain text into 30+ cool Unicode font styles. Bold, italic, script, gothic, circled. No signup, 100% private.

Favicon Generator - Free ICO, PNG Favicon Creator Online

Free favicon generator. Create favicons from text, emoji, image upload, or solid color. Export ICO + all PNG sizes in one ZIP. Live preview, 100% browser-based. AI cannot generate .ico binary files - we do.

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File Checksum Verifier - Verify MD5 SHA-1 SHA-256 SHA-512

Verify file checksums after downloading. Compute MD5, SHA-1, SHA-256, SHA-512 hashes from any file. 100% private browser processing, no upload.

File Opener - Open APK, RAR, DLL, DAT, BIN Online

Free online file opener. Detect, view, and extract 50+ file types (APK, RAR, ZIP, DLL, DAT, BIN, DOCX) using magic numbers. Browser-only, no upload, 100% private. AI cannot parse real binary files - we do.

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Flashcard Maker - Free Spaced Repetition Study Cards

Free flashcard maker with spaced repetition. Create unlimited decks, paste CSV/tab lists, study with Again/Hard/Good/Easy grading, track accuracy and…

Fraction Calculator - Add, Subtract, Multiply & Divide

Free fraction calculator. Add, subtract, multiply, divide fractions. Simplify, convert mixed numbers, compare fractions. Step-by-step solutions. No…

Free AI Chat - No Login, No Signup

Free AI chat powered by Llama 3.3 70B. No login, no signup, no tracking. Coding, writing, math, brainstorming. Conversations stay in your browser.

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Free AI Detector - Check If Text Is AI Generated

Free AI content detector using multi-model voting (Groq, Gemini, NVIDIA). Detect ChatGPT, Claude, Gemini text with sentence highlighting. No signup.

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Free AI Humanizer - Make AI Text Undetectable

Free AI humanizer with 5-stage DeAI pipeline. Bypass GPTZero, Turnitin, Copyleaks. No signup, no word limit, no paywall. Real MAGE, Burstiness, and brandonwise detector scores shown. Self-hosted.

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Free AI Paraphrasing Tool - Rewrite Text Online

Free AI paraphrasing tool that rewrites text while preserving meaning. 8 modes including humanizer makes AI text sound natural. No signup, no limits.

Free AI Plagiarism Checker - AI-Powered Content Originality Test

Free AI plagiarism checker that searches the web for duplicate content. Get similarity percentage, source URLs, and suggestions. No signup required.

Free AI PPT Maker - Generate Editable PowerPoint Slides

Free AI PPT maker with 4 professional styles. Generates real editable .pptx files in 10 seconds. No signup, no watermark, no daily limit. Uses Groq Llama 3.3 70B + PptxGenJS. 10 languages. AI cannot generate valid .pptx binary.

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Free AI Prompt Engineer - 8 Platforms 88 Templates Sandbox

Free AI prompt engineer. 88 ready-to-use prompts for ChatGPT, Claude, Midjourney, DALL-E, Stable Diffusion, Gemini, Llama, Copilot. Live test sandbox with…

Free AI Resume Builder - Professional Resume Generator

Free AI-powered resume builder. Enter your details and get a professionally formatted resume instantly. No signup required.

Free AI Sentence Rewriter - 8 Modes Side-by-Side

Free AI sentence rewriter. 8 modes (standard, fluency, formal, simple, creative, expand, shorten, humanize) with side-by-side sentence comparison and…

Free AI Translator - AI Multi-Language Translation

Free AI translator supporting 50+ languages. Translate text instantly with context-aware translations. No signup required.

Free ATS Resume Checker - Score & Scan Your Resume

Free AI-powered ATS resume checker. Score your resume 0-100 against any job description. Detects missing hard skills, soft skills, keywords, and ATS format issues. 5-priority Jobscan-style scoring, AI suggestions, 100% private. No signup, unlimited scans. 99% of Fortune 500 use ATS - this tool beats them.

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Free Audio Converter - Convert MP3, WAV, FLAC, OGG, AAC

Free online audio converter. Convert between MP3, WAV, FLAC, OGG, M4A, AAC, OPUS, AIFF. Adjust bitrate, sample rate, channels. No upload, 100% private, in-browser FFmpeg.wasm.

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Free Binary Hex Converter - Convert Binary to Decimal, HEX, ASCII

Free online binary hex converter. Convert between binary, decimal, hex, and ASCII text. Instant conversion, no upload needed. Developer tool for encoding.

Free BMI Calculator - Body Mass Index Checker

Free BMI calculator to check your body mass index. Supports metric and imperial units. Instant results with health category classification. No signup required.

Free Book Search & ISBN Lookup - 30M+ Open Library

Search 30+ million books by title, author, or ISBN-10/ISBN-13. Get covers, publisher, year, page count, subjects, and links to Open Library, Google Books, WorldCat, Amazon. AI cannot accurately recall book metadata - we use the live Open Library catalog. No signup, 100% private.

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Free Case Converter - Convert Text Case Online

Free online case converter. Convert text to uppercase, lowercase, title case, sentence case, camelCase, snake_case, kebab-case, and more. Instant results.

Free Citation Generator - APA, MLA, Chicago

Free AI citation generator. Generate citations in APA, MLA, Chicago, Harvard, and IEEE formats. Just describe your source and get a formatted citation.

Free Color Palette Extractor - Extract Colors from Image

Free online color palette extractor. Extract dominant colors from any image as HEX, RGB, HSL values. Download CSS variables or JSON. No signup required.

Free Currency Converter - 166+ Currencies Exchange Rates

Free currency converter. Convert between 166+ world currencies instantly. Live exchange rates, swap currencies, search by country or currency code.

Free Daily Horoscope - Personalized Astrology & Birth Chart

Free personalized daily horoscope. AI cannot compute real planetary transits or natal charts - we use astronomy-engine for accurate sun sign, moon sign, 2026 forecasts. 6 languages, 100% private.

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Free Email Signature Generator - Outlook Gmail HTML

Pro email signature generator. 10 table-based templates, MSO compatible, base64 photo embedding, click-to-call phones, social icons. Outlook + Gmail + Apple Mail ready. No signup, no tracking, 100% private browser tool. AI cannot produce email-client-compatible HTML.

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Frequently Asked Questions

Are all 323 developer tools really free?

Yes — every tool on DevTools Hub is 100% free with no signup, no trial, no daily limit, and no watermark. The site is supported by optional cloud functions and ad-free by design.

Do you upload my data to a server?

Most tools process everything in your browser. Only AI-backed tools (AI Chat, AI Detector, Image Generator, Story Animator, Translator, Paraphrasing Tool, Plagiarism Checker, Resume Builder, Cover Letter Generator, Citation Generator, ATS Resume Checker, AI Humanizer, Text-to-Speech, Text-to-Video, Text Summarizer, Math Solver, Grammar Checker, Subtitle Generator, and a few others) call a server API for GPU compute. Uploads are transient and never logged. Each tool page documents exactly what leaves your device.

Why use these tools instead of asking an AI chatbot?

AI chatbots hallucinate exact arithmetic, produce invalid JSON/XML, drop SVG attributes, and cannot compute dates, fractions, or compound interest reliably. DevTools Hub uses deterministic code — same input always yields the same verified output.

Do I need to create an account?

No account, no email, no tracking cookies. Open any tool, use it, close the tab. Your inputs never leave your browser unless you explicitly call a cloud-backed AI tool.

How often are new tools added?

New tools ship 2-3 times per week. The homepage shows a 323 tool count that updates automatically as new entries are added to the public manifest. See the sitemap.xml for the complete list.

Can I use these tools commercially?

Yes. The outputs you generate belong to you — use them in client work, internal tools, or commercial products without attribution. The tool code itself is MIT-licensed on GitHub.