Taggart
PDF/UA checker: free, unlimited, in your browser
Check any PDF against the Matterhorn Protocol, PDF/UA-1 and WCAG 2.1 AA. No page cap, no watermark, no account. Plus what checkers can and cannot tell you.
What it checks
Every machine-checkable failure condition in the Matterhorn Protocol 1.1, the PDF Association’s conformance testing model for PDF/UA-1: 31 checkpoints covering tagging, role mapping, metadata, character mappings, natural language, graphics, headings, tables, lists, notes, optional content, security, annotations, XObjects and fonts.
Each finding is mapped to its PDF/UA-1 clause and, where one applies, its WCAG 2.1 success criterion — so one check answers both questions.
Three profiles:
- PDF/UA-1 (ISO 14289-1) — every machine-checkable condition
- WCAG 2.1 Level AA — only conditions with a mapped success criterion
- IS 5568 — the WCAG-mapped set plus Taggart’s right-to-left conditions
Plus three things a conformance checker does not normally give you: a screen-reader preview showing exactly what is announced and in what order, a right-to-left analysis that detects visual-order Hebrew and Arabic, and a structure tree with per-element geometry.
What the severities mean
Findings are not a flat list, because the conditions are not equivalent.
Blocker — a machine-checkable PDF/UA-1 requirement is failed. Definite; the file cannot claim conformance until it is resolved.
Warning — the condition either has no machine test or passes one, but a heuristic says a human will reject it. A table with no header cells, a run of paragraphs that is obviously a list, a running head sitting in the reading order.
Needs a decision — genuine judgement. Taggart presents the evidence and records what you decide. It never auto-passes these, and it never fails them on a guess either.
What a checker cannot decide
The Matterhorn Protocol is explicit: of its 136 failure conditions, 87 can be decided by software, 47 require human judgement, and 2 have no specific test at all.
That ratio is the honest answer to “is my document accessible”. A clean checker run means the machine-decidable third is right. The rest — whether the alt text is true, whether the order is the author’s intent, whether that grid is a table — needs a person, and any tool reporting a compliance percentage is reporting the percentage of what it can see.
Using it
Drop a PDF in. Results in about a second for a typical document. Nothing to install.
Every finding carries a plain-language explanation, a line describing what a screen reader actually does when it hits the condition, the Matterhorn ID, the PDF/UA-1 clause, the WCAG criterion, and the page and structure path of every occurrence.
The report exports as JSON, which makes triaging a backlog a script rather than a project:
taggart check report.pdf --json | jq '[.findings[].ruleId] | unique'Check a PDF free → · Browse every failure condition →
Frequently asked questions
Is it really free, or is there a catch?
Free, unlimited and not a trial. Every machine-checkable Matterhorn condition, no watermark, no expiry, and no page cap once you have a free account — signed out it stops at 60 pages. Checking is commoditised — PAC, veraPDF and PDFix Lite all do it for nothing — so charging for it would only send you to one of them. Remediation is what a plan pays for.
How does it compare with PAC?
They largely agree, because both implement the same machine-checkable conditions. PAC is Windows-only and fixes nothing; Taggart runs anywhere and can also repair. Run both — two independent implementations agreeing is worth more than either alone, and Taggart records known disagreements in its rule file.
What can a checker not tell me?
Roughly a third of what matters. Whether alt text is accurate, whether the reading order matches the author's intent, whether a heading is a heading, whether a table is data or layout — all judgement. The Matterhorn Protocol itself says 47 of its 136 failure conditions require human judgement, and two have no test at all.
Do you store my document?
A signed-out check is processed and discarded — nothing is stored. Signed in, a check is kept only if you tick the box, and uploads expire after seven days.
Run your own file through it. The validator is free and unlimited — no page cap, no watermark, and no account at all up to 60 pages — so you can see exactly what you are dealing with before deciding anything.
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