SEO tools are everywhere, but most are locked behind signups, API limits, or subscription walls. I wanted something I could actually use without friction — so I built 6 tools over a weekend and open-sourced the approach.
The Tools
All run in-browser (4 client-side) or via lightweight server fetch (2 API routes). Zero external API costs.
1. Schema Markup Generator
Visual form → valid JSON-LD for FAQPage, Article, HowTo, Product, Organization, BreadcrumbList. Click "Copy HTML" and paste into your <head>. One-click link to Google Rich Results Test.
Why I built it: I was manually typing JSON-LD for every blog post. Now it takes 30 seconds.
2. LLMs.txt Generator
Input any URL, get llms.txt + llms-full.txt following the llmstxt.org standard. Fetches your sitemap, extracts titles/descriptions, formats everything.
Why it matters: AI assistants like ChatGPT and Claude check this file when users reference your site. No llms.txt = missed citations.
3. Hreflang Tag Generator
Add language/URL pairs, get self-referential hreflang HTML with x-default. Validates duplicates and missing tags.
Tiny tool, but saves me 10 minutes every time I add a new language to a site.
4. Meta Title & Description Analyzer
Pixel-accurate truncation check (Google measures in pixels, not characters). Live SERP preview, keyword density analysis, power word detection. Also flags "Best"/"Top" in titles per Google's Feb 2026 Core Update rules.
5. Robots.txt Tester
Paste your robots.txt, test any URL path against 15+ user agents — including GPTBot, ClaudeBot, PerplexityBot, and Google-Extended. Shows exactly which rule matched and whether it's Allow or Disallow.
Built this because blocking AI crawlers is becoming the default, but most people have no idea if their rules actually work.
6. OG Image Preview
Fetch any URL and see how it renders on Twitter, LinkedIn, Slack, and Discord. Each platform crops differently — this shows all four at once plus detects missing/broken tags.
Technical Decisions
- Client-side first: 4 of 6 tools run entirely in the browser. No server, no API, no data retention.
- Server fetch only when needed: LLMs.txt and OG Preview need to fetch external URLs (CORS), so they use Next.js API routes.
-
Zero API cost: No OpenAI, no paid APIs. Just
fetch()+ regex parsing. -
Dynamic routing: One
[tool]/page.tsxhandles stubs for unreleased tools; specific routes override when ready.
What I'd Do Differently
Schema Generator could use client-side validation against Schema.org spec (currently just generates, doesn't validate fields). Meta Analyzer's pixel width estimation is approximate — a Canvas-based measurement would be more accurate.
Try Them
All 6 tools are live at openaitoolshub.org/seo-tools. No signup, no API key. Feedback welcome.
What free SEO tools do you actually use daily? Curious what's missing from the landscape.
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