The best free SEO tools, all in your browser.
RankNibbler is the browser-based SEO toolkit thousands of developers, SEO pros, and agencies use every week to audit websites — without paying $99/month. 50+ tools, instant results, free PDF & CSV export. It even scores how citable your pages are for ChatGPT, Claude and Google AI Overviews — and every check is a free JSON API your own AI agents can call. No upsell, no limits.
Create a free accountOn-page audit & analysis
6 toolsSEO Checker
The main RankNibbler tool. Enter any URL, get a score out of 100 based on 100+ on-page checks — title tags, meta, headings, schema, alt text, readability, tech stack, accessibility, AI-search readiness, and more. PDF & CSV export.
Open tool →Site Audit
Enter a domain and RankNibbler crawls your sitemap.xml, discovers every page, then audits up to 1,000 pages automatically. Find your weakest URLs in minutes.
Open tool →Bulk URL Checker
Paste up to 20 URLs and get SEO scores for all of them at once. Each result has expandable details. Perfect for auditing a section or comparing competitor pages. CSV export.
Open tool →SEO Compare
Enter two URLs and an optional target keyword to see side-by-side comparison of every on-page factor. Find out exactly where your competitor outranks you.
Open tool →Keyword Rank Checker
Check your Google ranking position for any keyword and any URL. Useful for monitoring SERP position changes on the fly.
Open tool →SEO Score Checker
Understand how the RankNibbler score is calculated. Points per check, thresholds, and what "good" looks like.
Learn more →Monitoring & analysis
3 toolsUptime Monitoring
Watch any site around the clock and get an email the moment it goes down, with response-time and SSL-expiry checks. Free and unlimited.
Open tool →Page Change Monitor
Watch any page for changes and get told in plain English what moved — title, meta, schema, even the price. AI-powered, free and unlimited.
Open tool →TF*IDF Analyzer
Score the top-ranking pages for any keyword by TF*IDF and see which important terms your own page is missing. Free with an account.
Open tool →AI search & rank tracking
5 toolsRank Tracker
Track your Google positions by country and device, with the full top 100 captured for every keyword — see exactly who sits above you and how it changes. Free with an account.
Learn more →AI Visibility
See when ChatGPT, Gemini, Claude, Perplexity and Google's AI answers mention or cite your brand — a visibility score across six AI surfaces, tracked over time. Free with an account.
Learn more →AI Keyword Overview
Full keyword research from one search: volume with history, SEO difficulty, CPC, intent, the top 10 with backlinks, Google's AI Overview and hundreds of keyword ideas. Free with an account.
Learn more →AI Prompt Ideas
See the prompts people actually ask ChatGPT about any keyword — then run them and see which brands get recommended and which sources get cited. Free with an account.
Learn more →Reviews Monitor
Your Trustpilot rating, review count and latest reviews tracked automatically every week — watch your reputation next to your rankings. Free with an account.
Learn more →Link tools
6 toolsBroken Link Checker
Scan any page for dead links, 404 errors, and redirect chains. Checks up to 100 links per page with filters and CSV export.
Open tool →Redirect Checker
Check HTTP/HTTPS and WWW/non-WWW variants all redirect to the same canonical URL. Detects chains and temporary redirects.
Open tool →Link Analysis
Count internal vs external links, see anchor text, rel attributes, and nofollow ratios for any page.
Learn more →Nofollow Checker
Identify which links use rel="nofollow" and what percentage of your links are nofollowed.
Empty Links Checker
Detect links with no text or aria-label — a common accessibility and SEO issue.
Learn more →Backlink Audit
Your Authority Score with history, toxic link detection, new and lost links synced daily, and a ready-to-upload disavow file. Free with an account.
Learn more →Meta & content tools
7 toolsSERP Snippet Generator
Preview how your page appears in Google search results. Pixel-width meters show exactly where Google will truncate your title and description.
Open tool →Meta Tag Generator
Generate title, description, Open Graph, and Twitter Card tags from a simple form. Copy-ready HTML output.
Open tool →Title Tag Checker
Check any page's title tag presence, length, and how it'll display in search engines.
Learn more →Meta Description Checker
Verify meta description length (120–160 chars) for search result snippets and preview.
Learn more →Readability Checker
Flesch–Kincaid grade level, sentence length, syllable complexity for any page's content.
Learn more →Keyword Density Checker
Extract top 15 keywords and 2-word phrases from any page with frequency and density percentages.
Learn more →Word Count Checker
Count words on any URL. Flags thin content below 300 words. Shows text-to-HTML ratio.
Learn more →Structured data & social
4 toolsSchema Markup Generator
Create JSON-LD for FAQ, Article, Product, LocalBusiness, Event, and Recipe schema types. Copy-paste output.
Open tool →Structured Data Checker
Detect JSON-LD Schema.org markup on any page. Validates required fields for 15+ schema types.
Learn more →Open Graph Checker
Check Open Graph and Twitter Card tags so your links preview correctly on Facebook, LinkedIn, Slack, and X.
Learn more →Open Graph Preview
See how your links will appear when shared on Facebook, Twitter/X, LinkedIn, and Discord.
Open tool →Technical SEO
6 toolsRobots.txt Generator
Generate a valid robots.txt file with allow/disallow rules, sitemap reference, crawl-delay, and user-agent directives.
Open tool →.htaccess Redirect Generator
Create 301 redirect rules for Apache. Supports single redirects, HTTPS enforcement, and WWW canonicalisation.
Open tool →Heading Outline Extractor
Extract the H1–H6 tree from any webpage. Visualise heading hierarchy and find skipped levels.
Open tool →HTML Minifier
Minify HTML code to reduce file size. Removes comments, whitespace, and unnecessary attributes.
Open tool →Page Weight & Performance
Measure total page weight, number of requests, and get a full Core Web Vitals report via Google PageSpeed.
Open tool →Tech Stack Checker
Detect CMS, frameworks, analytics, CDNs, and 40+ technologies from the HTML source of any public URL.
Learn more →Technical checkers
5 toolsHTTPS & URL Checker
Verify HTTPS is enabled, URL structure is clean, and there are no obvious technical issues.
Learn more →Canonical URL Checker
Verify the canonical tag is set correctly to prevent duplicate content indexing issues.
Learn more →Robots Directives Checker
Detect noindex, nofollow, and crawl-blocking meta tags that could hide your content from Google.
Learn more →Image Alt Text Checker
Find every image on a page missing alt text. Critical for accessibility and image SEO.
Learn more →Accessibility Checker
Basic WCAG checks: form labels, skip nav, ARIA landmarks, linked-image alt text.
Learn more →AI search & developer API
2 toolsAI Search Readiness
See how citable your page is for ChatGPT, Claude, Perplexity and Google AI Overviews — Speakable schema, answer-first structure, direct-answer formatting, E-E-A-T signals, and the raw-vs-JS-rendered gap that hides content from AI crawlers. Scored on every audit. Almost no other free tool checks this.
Read the docs →Free SEO API & AI agents
Every check as clean JSON — wire it into CI pipelines, dashboards and scripts. Plus an MCP server + OpenAPI actions so ChatGPT and Claude can run audits for you directly. Free tier, no card required. The big suites charge for API access; ours is free.
Read the docs →RankNibbler vs. other SEO tools
How our free browser-based suite — on-page audits, full-site crawls, AI-search readiness, competitor analysis, uptime & AI change monitoring, and a free JSON API — compares to the bigger paid tools.
| Feature | RankNibbler | Ahrefs / SEMrush | Screaming Frog | Lighthouse |
|---|---|---|---|---|
| Price | Free | $99–$449/mo | Free (500 URLs) / £199/yr | Free |
| Account required | Optional (free) | Yes | Install required | No |
| On-page audit (100+ checks) | Yes | Yes | Yes | Partial |
| Full-site crawl | Yes (2,500 pages) | Yes | Yes (500 free) | No |
| Schema validation | Yes (15+ types) | Yes | Yes | No |
| Accessibility audit | Yes | No | Partial | Yes |
| Security headers audit | Yes | No | No | Partial |
| AI-search readiness (AEO/GEO) | Yes | Partial | No | No |
| Competitor page analysis (AI) | Yes | Yes | No | No |
| Uptime monitoring | Yes (free) | No | No | No |
| Page change monitoring (AI) | Yes (free) | No | No | No |
| Backlink analysis | Yes | Yes | No | No |
| Keyword rank tracking | Spot-check | Yes | No | No |
| Tech stack detection | 40+ | Partial | Partial | No |
| PDF / CSV export | Yes | Yes | Yes | HTML only |
| In-browser (no install) | Yes | Yes | No | DevTools only |
| REST API (JSON) | Yes (free) | Paid add-on | No | CLI |
| AI-agent ready (MCP — ChatGPT & Claude) | Yes | No | No | No |
Frequently asked questions
Are RankNibbler's SEO tools really free?
Yes. Every tool is free, with no daily limits and no premium tier. The core tools run right in your browser; a few advanced tools, like uptime and page-change monitoring, use a free account so we can email you alerts.
Do I need to create an account to use these SEO tools?
Most tools need no account; just paste a URL and run it. A few that work in the background, like uptime and page-change monitoring, use a free account (no card) so we can save your monitors and email you.
How does RankNibbler compare to paid SEO tools like Ahrefs, SEMrush, or Screaming Frog?
RankNibbler is a full on-page, technical and off-page suite — audits (title tags, meta, headings, schema, accessibility, page weight), full-site crawls, backlink analysis, competitor analysis, rank spot-checks, uptime & AI change monitoring, and a free JSON API — all free in your browser. Where Ahrefs and SEMrush pull ahead is the sheer scale of their backlink and keyword databases and historical data; Screaming Frog is a desktop crawler that needs installing and a licence for larger sites. For the vast majority of on-page, technical and competitor work, RankNibbler does the job without the subscription.
Can I use these tools for client SEO audits?
Yes. Every audit can be exported as a branded PDF or CSV for client reports. The tools have no usage limits so you can audit as many client sites as you need. White-label not available (the RankNibbler name appears in reports).
Do the tools work for any website platform?
Yes. RankNibbler tools work with any publicly accessible webpage — WordPress, Shopify, Wix, Squarespace, BigCommerce, Magento, headless setups, and custom-built sites. They fetch the HTML the same way a search engine crawler would. For password-protected staging sites, use the HTTP Basic auth fields on the homepage audit tool.
What about Core Web Vitals and page speed?
The Page Weight & Performance tool connects to Google's PageSpeed Insights API to return the full Core Web Vitals report (LCP, CLS, INP) for any URL. You can also see total page weight and request counts from the main audit.
Do you have an API or developer access?
Yes. Every check is available as a free JSON REST API — wire it into CI pipelines, dashboards and scripts. There's also an MCP server and OpenAPI actions, so ChatGPT and Claude can run audits for you directly. Free API key, no card required. (No standalone CLI yet, but the API covers programmatic use.)
How often are the tools updated?
We update check criteria whenever Google announces new ranking factors or deprecates old ones. The tools have been updated multiple times in 2026 to cover AI Overviews optimisation, Core Web Vitals INP metric, and expanded schema validation.