Not every SEO task needs a paid subscription. A handful of open-source and free tools can cover technical audits, keyword research, and site crawling without a monthly bill — here’s what’s actually worth using.
Technical SEO & Crawling
| Tool | What It Does | Best For |
|---|---|---|
| Screaming Frog (free tier) | Site crawler for technical audits | Sites under 500 URLs on the free tier |
| Google Search Console | Indexing, click/impression data, Core Web Vitals | Every site — this is non-negotiable and free |
| Bing Webmaster Tools | Bing indexing, backlink data, IndexNow submission | Sites wanting faster indexing and Bing/Copilot visibility |
| Lighthouse / PageSpeed Insights | Performance and Core Web Vitals auditing | Diagnosing speed issues page-by-page |
Content & Keyword Research
Fully free keyword research is limited — most volume data is proprietary. Google Search Console shows you what you actually rank for and get clicks on, Google Trends shows relative interest over time, and Google’s own autocomplete/related-searches are a legitimate free source of long-tail keyword ideas.
Where Open Source Falls Short
Backlink data is the biggest gap — building and maintaining a web-scale link index is expensive, which is why Ahrefs, Semrush, and Moz charge for it. Common Crawl’s public dataset is a genuinely open-source option here, but it requires technical skill to query and won’t match a purpose-built commercial index.
A Reasonable Free Stack
- Google Search Console + Bing Webmaster Tools for indexing and real performance data
- Screaming Frog free tier (or an open-source crawler) for technical audits on smaller sites
- PageSpeed Insights / Lighthouse for Core Web Vitals
- Google Trends and autocomplete for keyword direction
This covers most of what a small site needs. You’ll likely hit the ceiling first on backlink analysis and large-scale keyword volume data — that’s usually the point where a paid tool starts paying for itself.
FAQ
Can I run SEO entirely for free?
For a small site, largely yes. The gaps are backlink data and keyword search volume at scale.
Is Screaming Frog actually open source?
No — it’s free up to 500 URLs, then paid. It’s included here because it’s the most commonly used free-tier crawler, not because it’s open source in the strict sense.
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