SEO · OPEN SOURCE · 7 MIN
Claude SEO vs Seonaut: which free SEO checker should you run
Both are free, both are open source, and both will tell you what is broken on a site. That is where the resemblance ends. Claude SEO is an agent skill that reasons about a site inside Claude Code and hands back a prioritized fix list. Seonaut is a Go crawler you point at a domain and get a rule-by-rule report from. If you want a free SEO checker, you are choosing between an analyst and an instrument.
The distinction matters because the two fail in opposite directions. An instrument is deterministic: crawl the same site twice, get the same findings, in the same export format. An analyst is not: it reads, prioritizes, and explains, and you pay for the thinking in API tokens. Decide which half of the job you need, and the higher cost of one option or the other stops being the deciding factor.
Most readers should pick Claude SEO. If you are already in Claude Code, it asks for nothing to install, it tells you which findings matter and how to verify a fix, and it covers AI-search readiness that a plain crawler does not attempt. Pick Seonaut instead when you need a repeatable crawl you can diff over time, a dashboard someone else on the team can open, or a checker that costs nothing per run. The two answer different questions, and for most teams the audit question comes first.
The comparison at a glance
| Decision factor | Claude SEO | Seonaut |
|---|---|---|
| Licence and price | MIT, free skill; audits cost API tokens, roughly $6 per site in our runs | MIT, free self-hosted; hosted Lite tier free (one project, 500 URLs), Growth $9/mo (five projects, 10,000 URLs, recurring audits) |
| How it works | 25 sub-skills and 18 agents run inside Claude Code and reason about the crawl | A Go crawler with 79 documented issue types, self-hosted with Docker and MySQL or run hosted |
| Output | A prioritized, evidence-linked report with dependencies and a check for whether each fix worked | ECharts dashboards plus CSV, sitemap, and WACZ exports |
| Reproducibility | Scores shift between grader versions, so runs are comparable within a version, not across them | Fixed rule set; the same site produces the same findings |
| AI search readiness | Scores citability by AI answer engines, checks llms.txt and citation-friendly structured data | None; no AI features appear in the product or its site |
| Interface | Terminal only, no dashboard or stored history | Web UI with dashboards, single-user projects with no role model |
| Setup burden | Install the skill in Claude Code; nothing to host | Docker and MySQL to maintain, or the hosted tier; source builds need Go 1.25 |
| JavaScript rendering | Not documented for client-rendered pages | None; there is no headless browser in the codebase, so client-rendered pages audit badly |
That JavaScript gap is worth pausing on. Neither tool renders a JavaScript-heavy site the way a browser does, so both will misread a React application that builds its content on the client. If your site depends on client-side rendering, fix that problem before you shop for a checker, because it will distort the output of any free crawler in this class.
Factor by factor: who wins and why
Running cost: Seonaut. Self-hosted, Seonaut has no per-run fee at all; you pay for a small server. The hosted Lite tier is free with one project and 500 URLs, and Growth is $9 per month with five projects, 10,000 URLs, and recurring audits. Claude SEO is free software, but every audit spends API tokens, roughly six dollars for a full-site run in our testing. At daily frequency, that gap compounds.
Finding quality: Claude SEO. A crawler can tell you an image lacks alt text. It cannot tell you that the missing alt text is the least of your problems because your schema is duplicated in every blog post and your canonical tags point at the wrong host. Claude SEO's findings carry the observation behind them, their dependencies, and a check for whether the fix worked, which is the difference between a list of issues and a work order.
Reproducibility: Seonaut. Seonaut runs a fixed rule set, so crawling the same site twice produces the same findings, and the exports make it easy to diff two crawls. Claude SEO's grader changes between versions. On our own site the same pages scored 96 under v2.2.4 and 61 under v2.2.5 within a day, without the site changing in between. That is a real limitation for anyone tracking a score over months.
AI search readiness: Claude SEO. This is the skill's home turf and Seonaut does not compete here. Claude SEO scores pages for citability by AI answer engines, checks for self-contained answer blocks and llms.txt, and grades the structured data that gets a page cited. Seonaut has no AI features anywhere in the product or its site. If being cited in AI answers is part of your 2026 plan, the crawler will not help you with it.
Technical crawl coverage: Seonaut. Seonaut defines 79 issue types across page-level and site-wide checks, covering broken links and redirect loops, duplicate meta tags, heading order, hreflang, image and alt-text audits, canonical tags, orphan and dead-end pages, HTTPS, and TTFB. Its crawl options are unusually broad: bypass robots.txt, follow nofollow links, crawl from sitemaps or subdomains, check external links, and archive pages as WACZ. Claude SEO covers the same territory from an agent perspective but reports it as prose, not a queryable export.
Interface and team access: Seonaut. The findings land in Apache ECharts dashboards that anyone can open in a browser, which is a genuine advantage when the person who fixes the site is not the person who ran the crawl. Claude SEO lives in the terminal. Note Seonaut's own limit here: projects are single-user, with no roles or team model, so "anyone can open it" still means one login.
Infrastructure burden: Claude SEO. Seonaut needs Docker and MySQL, and the project ships no tagged releases, so installs track the latest container image and upgrades mean pulling it. Claude SEO has no server to maintain. This is the mirror image of the interface factor, and for a solo developer it can be the deciding one.
Which should you pick
You are in Claude Code and want to know what to fix first. Use Claude SEO. Run it against your own domain, work the prioritized list, and re-run after the fixes. The token cost is the price of the reasoning, and it is far below a consultant day rate.
You want a free checker on a schedule and a report you can hand over. Self-host or sign up for Seonaut. The fixed rule set, the exports, and the dashboard make it the better instrument for tracking a site over time and showing the work to someone else.
You run several sites and want both halves. Point Seonaut at each site for the crawl and the baseline, then run Claude SEO where the crawl output needs interpretation. Keep the crawl exports as your record, because they are the half that stays stable across versions.
A last note for anyone running either tool on a client's site. Seonaut identifies itself in server logs as SEOnautBot/1.0, so a client with alerting will see the crawl. Claude SEO appends its author's community links to major deliverables, so strip that before anything leaves the building. Both are free, and both come with a governance detail worth knowing before the first run.
The Seonaut side of this comparison draws on the GitHub repository, seonaut.org, and the project's install documentation; we have not run a crawl with it. The Claude SEO scores and costs come from audits we ran on our own production site.
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