Accessibility check
See what a screen reader will find in your PDF — and what it will miss.
Your files never leave your deviceDrop your PDF here
Nothing is changed: this check only reads the document.
Frequently asked questions
Does this check replace a full PDF/UA validation?
No, and the report says so itself. No free library validates the PDF/UA standard (ISO 14289-1) inside a browser: veraPDF is written in Java, the WebAssembly engines are commercially licensed, and the free online checkers receive your file on their server. Vellum therefore checks what can be read unambiguously from the file, and closes with the list of what it does not check: full PDF/UA conformance, the real reading order, tagged tables and lists, and the quality of the alternative texts.
What exactly does the report check?
Ten points. The document title (in the information dictionary and in the XMP) and the request to display it in the reader’s title bar; the declared language and its validity; the presence of real text page by page, as opposed to the image of a scan; the document’s tagging (MarkInfo /Marked and structure tree); the images tagged /Figure and their alternative text; the ranked headings H1 to H6; bookmarks beyond twenty pages; the tooltips on form fields; an estimate of the contrast; the PDF/UA identifier in the XMP; and the restrictions that would forbid extracting text for accessibility purposes. These points follow clauses 6.2, 7.1, 7.2 and 7.3 of veraPDF’s PDF/UA-1 validation profile, consulted on 17.09.2026.
Why is the contrast announced as an estimate?
Because that is what it is. Vellum draws the first ten pages at reduced resolution (about 100 dots per inch), groups the colours, keeps the most frequent one as the background, discards the in-between shades that are far less populated than a darker ink — those are the anti-aliasing pixels of letter edges — then computes the WCAG contrast ratio between the background and each remaining ink colour. The threshold used is 4.5:1, the one from success criterion 1.4.3 of WCAG 2.1 at level AA (w3.org/TR/WCAG21, consulted on 17.09.2026). This measurement does not know the size of the characters — WCAG only asks for 3:1 beyond 18 point — does not tell apart text laid over a photograph, misses a single light-grey line buried in a long black text, and does not look past the tenth page.
Can Vellum fix what the report flags?
Only in part, and it says so point by point. A page without text is recovered with character recognition; a missing title is written with the Metadata tool; encryption restrictions are lifted with the Unlock tool. Vellum, however, cannot add structure tags or alternative text for images: that requires understanding the meaning of the document, and is done in the software that produced it. Vellum’s Metadata tool also does not write the document language or the request to display the title, two settings that live elsewhere in the file.
Who is required to make their PDFs accessible?
In Switzerland, the Disability Discrimination Act (LHand, SR 151.3, in force since 2004) requires public authorities to make their digital services usable by everyone, and the federal administration applies the eCH-0059 standard for that, whose version 3.0 was approved on 25.06.2020 and adopts WCAG 2.1 at level AA. In the European Union, the European Accessibility Act (Directive (EU) 2019/882) has applied since 28.06.2025 to many private products and services. Sources consulted on 17.09.2026: ebgb.admin.ch, ech.ch and the European Commission’s AccessibleEU centre.