What is llms.txt?
"llms" stands for Large Language Models — the AI systems behind ChatGPT, Claude, Perplexity, and Google's Gemini. llms.txt is a plain-text Markdown file you place at the root of your domain (at https://yoursite.com/llms.txt) to tell large language models what your site is about and which pages matter most. It's a positive signal — the opposite of robots.txt, which only controls access. Think of it as a curated tour guide for AI: "here's who we are, here are our best pages, here's how to describe us accurately."
When ChatGPT, Claude, Perplexity or Google's AI Overviews generate an answer mentioning your brand or topic, a well-written llms.txt gives them a clean, authoritative source to pull from — instead of guessing from scraped HTML. The format follows a simple spec proposed at llmstxt.org: an H1 with your brand name, a one-line summary in a blockquote, optional descriptive paragraphs, then H2 sections listing your key URLs with one-line descriptions. That's it. No YAML, no schema, no vendor lock-in.
The file is still a new standard, but adoption is rising — Anthropic, Cloudflare, Mintlify, and most AI-native developer tools publish their own. Adding one today is a cheap way to stand out while almost no one has one yet.
Why BYOK? Because agency-priced llms.txt is absurd
An SEO agency writing a bespoke llms.txt for a 200-page site will quote you somewhere between $500 and $2,000. The actual work — feeding page content to an LLM and asking for one-sentence descriptions — costs between $0.20 and $3.00 in API fees depending on site size and model choice.
Our AI builder is the same workflow an agency runs, but you bring the key, you own the output, and you skip the markup. If Claude or GPT is already part of your stack, the marginal cost per site is effectively zero.
What the AI builder actually does
- Crawls your sitemap. Pulls every URL, ranks them by likely importance (depth, keyword signals), and picks the top 15–20 pages.
- Fetches the content of each page. Via our server-side proxy with SSRF protection and size limits — nothing touches your origin that wouldn't touch it from any other browser.
- Writes tailored descriptions. The model reads each page's actual content and writes a one-line summary in your brand's voice. Not templates. Not "replace with description."
- Structures a valid llms.txt. Proper Markdown, correct hierarchy (H1, blockquote summary, H2 sections), following the llmstxt.org spec.
- Lets you edit before shipping. Full editable output. Copy, download, or paste directly into your root directory.
Free vs AI Builder at a glance
| Free Generator | AI Builder (BYOK) | |
|---|---|---|
| Site structure | Sitemap + homepage meta | Full content of top pages |
| Page descriptions | Auto-generated titles from URL slugs | AI-written, content-aware, on-brand |
| Summary / tagline | Pulled from meta description | Rewritten by the model for clarity |
| Setup time | 5 seconds | 30–90 seconds (AI pass) |
| Cost to you | Free | Your API usage (pennies) |
| Access | Public | Access code required |
Cost estimate
Per site, with roughly 15 pages crawled:
- Claude Haiku 4.5: ~$0.05–$0.15 per site
- Claude Sonnet 4.6: ~$0.30–$0.80 per site
- GPT-4o-mini: ~$0.03–$0.10 per site
- GPT-4o: ~$0.40–$1.20 per site
Exact cost depends on page lengths. For agencies running dozens of sites, this is orders-of-magnitude cheaper than manual writing.
Who this is for
- SEO agencies running llms.txt as a deliverable for multiple clients — generate fast, edit, invoice the value, not the labor.
- In-house marketers who need their site cited correctly by ChatGPT, Claude, and Perplexity answers.
- Developers adding llms.txt as part of a launch checklist without writing boilerplate by hand.
- Large-site owners where a free template generator can't produce a meaningful file.
FAQ
Is my API key safe?
Your key enters our proxy server-side function only to forward the one request to Anthropic or OpenAI. We don't log request bodies, don't persist keys, and don't keep request history beyond what Vercel's standard access logs capture (which don't include headers or body content). If you're uncomfortable with the proxy, you can also run the tool locally — it's a static page.
Which AI providers do you support?
Anthropic (Claude) is supported at launch — Haiku 4.5 for fast/cheap runs, Sonnet 4.6 for higher-quality output. OpenAI (GPT-4o, GPT-4o-mini) is supported too. Bring whichever key you already have.
How do I get an access code?
Join the waitlist on our homepage, or reach out via the footer. Codes are limited during early access.
Will the output be perfect?
The AI writes a strong first draft — typically 80–95% shippable. We always show you the raw output in an editable textarea so you can tighten voice, remove sections you don't want featured, or reorder priorities before publishing.
Do I need both the free and the AI tool?
No. The free generator is the right choice if you want a quick template for a small or straightforward site. The AI builder is for when descriptions matter — marketing-critical pages, large sites, or content-heavy brands where a templated summary won't do it justice.
Can I use this for client sites?
Yes — agency use is the ideal use case. Nothing in the tool identifies you or your clients to us, and the output is yours to ship under your own brand.