Check it yourself first. Two real ReflowPDF exports, both valid PDF/A-3a:
Run either through veraPDF on the PDF/A-3a profile (or Acrobat Preflight). Result: compliant, zero failures — the report clears 41,944 individual checks. Straight out of an HTML-to-PDF engine, in the browser. Here’s what that format is, why it’s hard, and the twist that makes our version different.
What PDF/A-3a is
PDF/A (ISO 19005) is the archival PDF standard. The promise: a file that is fully self-contained and will render identically decades from now — every font embedded, colour pinned to an ICC profile, no external references, no encryption, no “open this in the right viewer or it breaks.” Government bodies, courts, and records systems mandate it precisely because a plain PDF makes none of those guarantees.
The suffix decodes like this:
- 3 — the PDF/A-3 part — permits arbitrary embedded files inside the archive (PDF/A-1 and -2 forbid attachments entirely).
- a — the accessibility conformance level — requires a complete tag tree: the same logical structure (headings, tables, lists, reading order, language) that screen readers rely on. The lesser level “b” only guarantees visual reproduction.
So PDF/A-3a = archival + accessible + can carry attachments. It’s the strongest single contract a PDF can make.
Why most HTML-to-PDF tools can’t produce it
It stacks two hard requirements that most engines fail individually:
- 1The tag tree (level “a”). Most HTML-to-PDF engines flatten the document to drawing operators and discard structure — there’s nothing to tag. (We solved this for PDF/UA accessibility first; PDF/A-3a reuses it.)
- 2The archival rules. Every font must be embedded (no relying on the reader’s Arial), a valid OutputIntent with an embedded ICC colour profile must be present, the XMP metadata must declare
pdfaidconformance, and prohibited features (encryption, certain transparency, external links to files) must be absent.
Hit one but not the other and veraPDF rejects the file. ReflowPDF does both because the editor already works on the document’s real structure — the tags come for free, and the export pipeline adds the archival layer: embeds the fonts it used, bakes in an sRGB OutputIntent, writes the pdfaid identifier, and refuses to encrypt.
The twist: an archive you can still edit
Here’s what normal PDF/A can’t do. A flattened archival PDF is frozen — to change it you start over.
PDF/A-3 allows embedded files, and ReflowPDF uses that to store the document’s own editable source inside the archive, as a standard Associated File (/AFRelationship /Source). So a ReflowPDF PDF/A-3a is a compliant, frozen-for-the-record archive that still re-opens and edits in ReflowPDF months later — no re-conversion, no quality loss. Archival integrity and a living document, in one file. We verified the round-trip still works on the same files that pass veraPDF.
Honest: it’s not the right default for everyone
PDF/A-3a is a deliberate trade, not a free upgrade:
- Bigger files — embedding every font (no system-font shortcut) adds weight a simple PDF avoids.
- A stricter contract — the “frozen, self-contained” guarantees mean some things (encryption, certain dynamic content) are off the table by design.
- Most users don’t need it — a normal export from ReflowPDF is already tagged and accessible. PDF/A-3a is for long-term archival and compliance: records retention, legal/government submissions, institutional archives, and accessibility mandates (EU Accessibility Act, Section 508).
That’s why it’s an explicit choice, not the default.
How to use it
Toggle “Export as PDF/A-3a” in Page Settings or your Account settings (the two stay in sync), then export. It’s a Pro/Max feature — the rest of the editor is unchanged. Your everyday exports stay normal, tagged PDFs; flip the switch when a document needs to go in an archive or a compliance submission.
Then download the samples above and run them through veraPDF — or open the editor and make your own. Zero failures.