Web Content Accessibility Guidelines. WCAG defines contrast ratios for readable text. AA is the common target; AAA is stricter.

What ratio do I need?

AA: 4.5:1 for normal text, 3:1 for large (18px+ or 14px+ bold). AAA: 7:1 and 4.5:1 respectively.

Yes. Free with no signup required.

Does it work with dark mode?

Yes. Test any foreground/background pair—light on dark or dark on light.

What hex format is supported?

Use #RGB (e.g. #f00) or #RRGGBB (e.g. #ff0000). We parse both.

Free Color Contrast Checker Online

Test foreground and background color pairs against WCAG 2.1 AA and AAA guidelines. Ensure your web designs are readable and fully accessible to all users.

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20 tools that do the work for most visitors

These are the tools people actually come back for. Each runs free, in your browser or in a stateless processing request, with no account and no watermark on the output.

🖼️Image CompressorShrink JPEG, PNG, and WebP files by 40–80% without visible quality loss. Useful for Shopify product photos, Squarespace uploads, or Gmail attachments when your image is a few megabytes too heavy. Drag a file in and the compressed version is ready in under two seconds. 📄Compress PDFReduce a PDF's file size by 30–70% so it fits under Gmail's 25 MB cap or a government portal's 10 MB limit. The tool downsamples embedded images and strips redundant object streams, then rebuilds a clean, readable document. Text layers stay sharp; scanned pages shrink the most. 📑Merge PDFsCombine multiple PDF documents into a single file while preserving bookmarks, form fields, and original page orientation. Drag files into the order you want, and the merged PDF downloads instantly. Common uses: stitching invoice, contract, and cover letter into one attachment before sending to a client. ✂️Background RemoverAutomatically cut the background out of any photo using AI segmentation and get a transparent PNG back. Works on product photos, headshots, and pets. Typical use: Etsy and Amazon sellers who need clean catalog images without paying a subscription to Remove.bg or Canva Pro. 📐Resize ImageResize a photo to exact pixel dimensions or scale by percentage. Built-in presets for Instagram square (1080×1080), Facebook cover (820×312), LinkedIn banner (1584×396), and YouTube thumbnail (1280×720). Aspect-ratio lock prevents accidental stretching; output can be JPEG, PNG, or WebP. 📝PDF to WordConvert a PDF into an editable Microsoft Word (.docx) file while keeping paragraph structure, tables, bullet lists, and most formatting intact. Useful when someone sends you a contract as a locked PDF and you need to make tracked changes before sending it back to them. 📱QR Code GeneratorCreate high-resolution QR codes for URLs, plain text, Wi-Fi credentials, contact cards, and email addresses. Download as PNG or SVG at up to 1000 pixels. Scannable by every modern phone camera. Ideal for event check-ins, restaurant menus, business cards, and product packaging. { }JSON FormatterPretty-print and validate JSON in your browser with two-space or four-space indentation, sorted keys, or compact minified output. Full syntax-error reporting shows the exact line and column where a comma is missing. Runs entirely client-side — your payload never leaves your computer. 📝Word CounterCount words, characters (with and without spaces), sentences, paragraphs, and estimated reading time. Designed for students meeting a 500-word essay limit, copywriters billing by word count, and authors tracking daily output. Includes keyword density analysis and Flesch–Kincaid readability scoring. 🔤Base64 Encoder / DecoderConvert text or small files to Base64 and back. Common uses: embedding an image directly in an email signature, encoding an API payload, decoding a JWT header, or inspecting the data: portion of a URL. Runs in your browser — nothing is transmitted to the server. 🔒Hash GeneratorGenerate MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes from any text input. Useful for verifying file integrity, creating deterministic cache keys, or checking that a password hash matches what is stored in a database. Results appear instantly; runs entirely in your browser. 🎨Color PickerPick a color visually and get its HEX, RGB, HSL, HSV, and CMYK values, or enter any code and see the swatch. Built-in accessibility contrast checker tells you whether the chosen color pair passes WCAG AA on body text, headings, or large UI elements. 🔑Password GeneratorGenerate strong passwords with configurable length (8–64), character sets (uppercase, lowercase, digits, symbols), and ambiguity filters that exclude characters like O/0 and l/1. Entropy score estimates how long a brute-force attack would take. Runs locally — passwords never touch the network. 📄Text to PDFTurn plain text, pasted notes, or long-form content into a clean, printable PDF document with selectable margins, font size, and page size (A4 or US Letter). Useful when you need to send meeting notes as a single file rather than a long email body that gets threaded. 📑Split PDFExtract specific pages from a PDF or split one long document into individual per-page files. Page-range syntax supports complex selections like "1-5, 8, 11-13". Useful when a single 80-page scan needs the signature page delivered separately to a different recipient. 🔄Image Format ConverterConvert between JPEG, PNG, WebP, BMP, and GIF with adjustable quality and lossy/lossless settings. Most common need: converting an old iPhone HEIC or Windows BMP into a format every website and email client accepts. WebP output is typically 25–35% smaller than equivalent JPEG. 🖊️PDF EditorAdd text, signatures, highlights, redactions, and images directly onto an existing PDF, right in your browser. No installation, no account, no Adobe Acrobat subscription. Redaction is true redaction — the content is removed from the file, not just covered with a black rectangle that can be peeled back later. ▶️YouTube Thumbnail DownloaderPaste any YouTube video URL and download the thumbnail in every available resolution, from 120×90 to 1280×720. Useful for making reaction thumbnails, citing videos in presentations, or collecting reference imagery. Works on full videos, Shorts, and unlisted videos as long as you have the URL. 🧾Invoice GeneratorBuild a professional invoice with your business name, logo, line items, tax, and totals, then download it as a PDF ready to send. No signup or account required, nothing is saved server-side. Designed for freelancers and small businesses who bill a handful of clients per month. (.*)Regex TesterTest regular expressions against sample text and see every match highlighted, with capture groups labelled. Supports JavaScript, PCRE, and Python flavor differences. Useful for validating an email-parsing pattern, building a form-input regex, or debugging why your log-extraction pattern keeps matching the wrong field.

Built by one developer, deliberately kept simple

GoToolsOnline is an independent project built and run by Ben Praveen J, a full-stack developer in Tamil Nadu, India. The brief was narrow: build the kind of tools site I personally wished existed — one that does not ask for an account, does not stamp watermarks on your output, does not limit free usage to two files per day, and does not bury a 30-second task under a "Start Free Trial" button.

The site does not host thousands of templated variations of the same converter. Every tool here was written for this site and is maintained by the same person who answers contact@gotoolsonline.com. If something breaks, it gets fixed. If a tool is missing, email and I will often build it.

How your files are handled

Text tools like the word counter, JSON formatter, Base64 encoder, and hash generator run entirely in your browser — the data you paste never leaves your computer. File tools like PDF compress, image compression, and background removal upload over HTTPS, process in server memory, return the result, and discard the original. There is no archival storage path for user uploads. Connections use TLS; analytics are anonymised (IPs are hashed); cookie consent is handled through Google Consent Mode v2 with explicit accept and reject controls.

How this is funded

One revenue source: Google AdSense. No paid tier, no premium plan, no credit-card form hiding behind a feature. Ads pay for the VPS, the domain, and a little compensation for the time that goes into building and maintaining the tools. If you prefer, the cookie banner lets you decline personalised advertising — the tools still work the same either way. Read the full story on the about page.

Frequently Asked Questions

What happens to a file after I upload it?: File-based tools (PDF, image, media) receive your upload over HTTPS, process it in server memory for the duration of your request, return the result, and discard the original. There is no archival storage path for user uploads. Text tools run entirely in your browser and never transmit the data you paste. See the privacy policy for the full data-handling detail.
Are outputs watermarked or quality-limited?: No. The output you download is exactly what the tool produced — no watermark stamp, no logo, no "upgrade to remove this" nag. The free PDF compressor gives the same quality as the paid one because there isn't a paid one. This applies to every tool on the site, including PDF merge, image compression, and background removal.
What file size limits apply?: Most file tools accept uploads up to 500 MB. Image tools typically handle up to 50 MB per image. PDF tools support documents up to 500 MB. If a file is larger, compress or split it first using the free tools on this site. There are no daily usage limits.
Can I process multiple files at once?: Yes, for tools where batch processing makes sense. The image compressor accepts multiple images in one upload, PDF merge works on any number of documents, and the collage maker takes multiple photos at once. For single-file tools, run them repeatedly — there is no daily cap.
Which browsers are supported?: Chrome, Firefox, Edge, Safari, Opera, and Brave on desktop and mobile. No extensions or plugins required. The site works on Windows, macOS, Linux, Android, and iOS.
Who builds and runs GoToolsOnline?: The site is built and maintained by Ben Praveen J, a full-stack developer based in Tamil Nadu, India. There is no team, no investor, no VC — the same person who writes the tools also answers contact@gotoolsonline.com. You can also verify the human on the other side via LinkedIn. For the full story, see the about page.

Part of Media tools: See all Media tools.

Color Contrast Checker: Check WCAG color contrast ratios for text accessibility. Enter a foreground (text) color and background color to see if the combination meets WCAG AA or AAA standards. Essential for designers and developers building accessible websites and apps.

Quick steps

Pick or enter a foreground (text) color and background color using the…
View the live sample text to see how the combination looks.
Read the contrast ratio and WCAG pass/fail for AA Normal, AA Large…

Color Contrast Checker vs desktop software

Feature	Color Contrast Checker	Desktop software
Install required	No	Yes
Works on phone & desktop	Yes	Varies
Free to use	Yes	Often paid
Signup needed	No	Sometimes

What is Color Contrast Checker?

Check WCAG color contrast ratios for text accessibility. Enter a foreground (text) color and background color to see if the combination meets WCAG AA or AAA standards. Essential for designers and developers building accessible websites and apps. Supports hex colors and live preview.

How to use Color Contrast Checker

Pick or enter a foreground (text) color and background color using the color picker or hex input.
View the live sample text to see how the combination looks.
Read the contrast ratio and WCAG pass/fail for AA Normal, AA Large, AAA Normal, and AAA Large.

Why use this tool?

Color contrast checker WCAG helps ensure text is readable for users with low vision or color blindness. AA requires 4.5:1 for normal text and 3:1 for large text; AAA requires 7:1 and 4.5:1. Many users search for 'accessibility contrast checker' or 'WCAG color contrast'. Our tool run online—no data is sent. Free accessibility tools help designers meet ADA and Section 508 requirements.

FAQ

What is WCAG?: Web Content Accessibility Guidelines. WCAG defines contrast ratios for readable text. AA is the common target; AAA is stricter.
What ratio do I need?: AA: 4.5:1 for normal text, 3:1 for large (18px+ or 14px+ bold). AAA: 7:1 and 4.5:1 respectively.
Is this tool free?: Yes. Free with no signup required.
Does it work with dark mode?: Yes. Test any foreground/background pair—light on dark or dark on light.
What hex format is supported?: Use #RGB (e.g. #f00) or #RRGGBB (e.g. #ff0000). We parse both.

Color Contrast Checker — In-Depth Guide

Color contrast checking ensures that text is readable against its background color. Web Content Accessibility Guidelines require minimum contrast ratios of four point five to one for normal text and three to one for large text. This tool calculates the exact ratio between any foreground and background color pair and reports whether it meets accessibility standards.

Web designers and developers use contrast checkers during the design phase to ensure their color palettes are accessible to users with visual impairments. Approximately eight percent of men and half a percent of women have some form of color vision deficiency. Meeting contrast guidelines ensures your content is readable by the widest possible audience.

Accessibility auditors rely on contrast checking tools when evaluating websites for compliance with WCAG guidelines and legal requirements like the ADA or Section 508. Documenting contrast ratios for key text elements provides evidence of compliance during audits. This tool generates clear pass or fail results against both AA and AAA conformance levels.

Tip: test contrast for all text sizes on your site, not just body copy. Navigation links, button labels, placeholder text, and error messages all need sufficient contrast. Dark mode designs need separate contrast verification. When a color pair fails, try adjusting lightness rather than hue to improve contrast while maintaining your color scheme's overall aesthetic.

Also try

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