You scan a lease agreement, a notarial deed, or payslips to keep them. A few years later, you open the file — and find fonts that no longer display correctly, missing images, a broken interactive layer.
That's exactly the problem PDF/A solves since 2005. Here's what to know before archiving important documents.
PDF/A in one sentence
PDF/A (ISO 19005) is a PDF variant designed to guarantee perfect readability of a document over the very long term, regardless of the software or system that opens it 30 years from now.
Concretely, a PDF/A is a PDF with additional constraints:
- All fonts must be embedded (no reference to a system font)
- No external content (no URL-linked images, no JavaScript, no active forms)
- No encryption (the file must be openable by any reader)
- Standardized metadata (XMP, RDF) for archive classification
- Closed color spaces (no proprietary ICC profile)
In short: a PDF/A is self-contained. Everything it needs to display correctly is in the file.
Why a "regular" PDF isn't enough
A regular PDF can reference:
- A system-installed font — which may not exist in 20 years
- An external link to a third-party PDF — whose URL will have changed
- An embedded Flash plugin — whose format died in 2020
- A specific color profile from a 2003 printer
When you open it in 2050, the application will display "default font" instead of the original, the image will be missing, the form will no longer work.
For a temporary marketing document, no problem. For a decade-retention contract, notarial deed, or accounting archive, that's unacceptable.
PDF/A levels: 1, 2, 3
Three main families, each with two conformities (a and b).
PDF/A-1 (2005)
The original standard. Doesn't support transparency, layers, or modern OpenType fonts.
- PDF/A-1a: strict, accessible (Tagged PDF — useful for screen readers)
- PDF/A-1b: visual conformity only (rendering will be identical, but not necessarily accessible)
PDF/A-2 (2011)
Supports JPEG2000, transparency, layers, and embedding PDF/A inside PDF/A.
- PDF/A-2a: strict + accessible
- PDF/A-2b: visual only
- PDF/A-2u: visual + guaranteed-searchable text (Unicode)
PDF/A-3 (2012)
Like PDF/A-2 but allows embedding arbitrary files (CSV, XML, original Word). Heavily used for electronic invoices: visual PDF + structured XML in a single file.
- PDF/A-3a / 3b / 3u (same nuances as PDF/A-2)
Which to choose?
| Use case | Recommended level |
|---|---|
| Simple archive (contract, quote) | PDF/A-1b |
| Archive with accessibility (public admin) | PDF/A-1a or PDF/A-2a |
| Modern PDF with transparency/layers | PDF/A-2b |
| Electronic invoice (Factur-X, ZUGFeRD) | PDF/A-3 |
| Academic publication | PDF/A-2u or PDF/A-3u |
For 95% of cases, PDF/A-2b is the ideal compromise: modern, broad compatibility, reasonable size.
When PDF/A is legally mandatory
A few European contexts where PDF/A is required:
- French public archives: required by SIAF (Interministerial Service of French Archives)
- Dematerialized public tenders: most platforms accept only PDF/A
- Factur-X / ZUGFeRD (FR + DE electronic invoice standard): mandatorily PDF/A-3 based
- Commercial court registries: annual accounts deposits in PDF/A
- Probative archiving (eIDAS, AFNOR NF Z42-013 certification): PDF/A-1 or PDF/A-2 mandatory for legal value
How to verify a PDF is really PDF/A
Two reliable methods:
1. XMP metadata
Open the PDF with a metadata-capable editor (Adobe Acrobat, or Sumatra). PDF/A files declare in their metadata:
pdfaid:part = "2"
pdfaid:conformance = "B"
2. veraPDF (free open-source validation)
veraPDF is the reference tool to validate PDF/A conformity. Open-source, multiplatform, required by professional archivists.
How to convert a regular PDF to PDF/A
Several options depending on context:
Online — PDFly (coming soon)
PDFly's PDF/A converter is coming soon. Conversion requires server processing (embedding missing fonts, ISO checks), so it will run on our servers in Paris (EU), with files deleted immediately after processing. Like every PDFly tool, it will be free — with fair-use limits, since each conversion uses real server resources.
Leave your email on the PDF to PDF/A page to be notified at launch.
Local software — Adobe Acrobat
File → Save As → choose "PDF/A" in dropdown. Included in Adobe Acrobat Pro (paid).
Command line — Ghostscript
Free and powerful for advanced uses.
gs -dPDFA=2 -dBATCH -dNOPAUSE -sDEVICE=pdfwrite \
-sOutputFile=archive.pdf source.pdf
Advantage: scriptable, ideal to convert 1,000 files in batch.
Common pitfalls to avoid
- Converting an already-signed PDF to PDF/A — the digital signature can be invalidated. Convert first, sign after.
- PDF/A with interactive content — JavaScript forms break on conversion. Save the active form separately.
- PDF/A without validation — always validate with veraPDF before legal archiving.
- PDF/A-3 for simple archive — overkill, choosing A-1b or A-2b is enough in 95% of cases.
In summary
PDF/A isn't an administrative gadget: it's a technical guarantee of readability over 30 or 50 years, legally required in several European contexts.
For most professional archives: PDF/A-2b is the ideal modern standard. Conversion takes less than a minute, but the benefit runs for decades.
Until PDFly's converter launches, Ghostscript + veraPDF is the free, reliable combo. Get notified when PDFly's PDF/A converter is ready — free, EU-hosted.