Free Tool
llms.txt Validator
Validate your llms.txt or llms-full.txt against the official llmstxt.org spec — line-level errors, fix suggestions, a live preview, and optional link checks.
What the llms.txt Validator checks
The llms.txt standard gives large language models a clean, curated map of your most important content. A malformed file can cause AI systems to misread your structure or miss key pages — so this validator checks every requirement from the official llmstxt.org spec and reports each problem on the exact line, with a concrete fix.
- Single H1 title — exactly one
# Project Name, as the first line (required). - Blockquote summary — a short
> summaryafter the H1 (recommended). - Section link lists —
## Sectionheadings with items in the- [name](url): notesformat. - Valid links — absolute http(s) URLs, no duplicates, optional reachability check.
- Size & count guidelines — under ~50KB and ~100 links for
llms.txt; up to 500KB forllms-full.txt.