The problem this solves
Font errors are among the most technically complex PDF accessibility failures. A document can display perfectly on screen while still containing fonts that are missing their embedding data, have broken CID mappings, use incorrect encoding tables, or contain malformed glyph structures.
Each of these defects causes the PDF to fail PDF/UA (ISO 14289) and PDF/A (ISO 19005) compliance audits – and each requires a different repair technique.
Fixing them manually requires deep PDF internals knowledge and is not feasible at scale.
What this action does
Font Fix (callas software) integrates the callas pdfToolbox engine – an industry-standard PDF processing engine developed by callas software GmbH and used in professional print and publishing workflows worldwide – directly into PDFix Desktop and PDFix SDK. The action runs as a Docker container on your local machine, analyzing every font in the document and automatically applying the appropriate correction for each issue found.
It handles the full range of PDF font compliance problems in a single pass:
- Missing font embeddings – embeds fonts that are referenced in the PDF but not included in the file, ensuring reliable rendering across assistive technologies
- CID font errors – corrects malformed character identifier structures that prevent screen readers from mapping glyphs to characters
- Encoding failures – repairs broken or missing encoding tables that cause text extraction and copy-paste to produce garbled output
- Glyph structure problems – fixes malformed glyph definitions that cause rendering failures and accessibility validation errors
- Font substitution – applies controlled substitution where embedding the original font is not possible, preserving visual fidelity and compliance
The output is a PDF where all font-related PDF/UA and PDF/A compliance issues are resolved, ready for validation.
Pricing: Free for unlimited use in PDFix Desktop. SDK integration for automated pipelines requires a callas software license for commercial use.
Action
| Free Desktop · Paid SDK · Local | Font Fix Callas | Automatically detects and fixes font-related issues in PDF documents to improve compliance with PDF/UA and PDF/A standards. It embeds missing fonts, applies controlled font substitution, and corrects common CID, encoding, and glyph structure problems to ensure reliable rendering and accessibility. |
Frequently Asked Questions
What types of PDF font errors does this action fix?
Font Fix (callas software) repairs four categories of font compliance failures: missing font embeddings (fonts referenced in the PDF but not included in the file), CID font errors (broken character identifier structures), encoding table failures (incorrect or missing tables that cause garbled text extraction), and glyph structure problems (malformed glyph definitions that cause rendering or validation errors). It also applies controlled font substitution where original font embedding is not possible.
Which accessibility standards does this action support?
Font Fix (callas software) addresses compliance requirements for both PDF/UA-1 (ISO 14289-1) and PDF/A (ISO 19005). PDF/UA requires that all fonts used in an accessible PDF are properly embedded and have complete encoding data. PDF/A additionally requires that fonts be fully embedded for long-term archival fidelity. This action is the only PDFix Marketplace font repair action that covers both standards.
Is this action free to use?
Use in PDFix Desktop is free and unlimited. Building Font Fix (callas) into an automated workflow using PDFix SDK requires a callas software license for commercial deployment. For licensing information, contact the PDFix sales team.
Does this require an internet connection?
No. The action runs entirely on your local machine inside a Docker container. No document data is transmitted to callas software, PDFix, or any third party during processing.
What is the difference between Font Fix (callas software) and Font Fix (PDFix)?
Both actions repair PDF font accessibility issues, but they use different engines and address different problem depths.
Font Fix (PDFix) uses OCR to recover missing Unicode mappings – it is 100% free, fully open-source, and ideal for documents where glyphs display correctly but lack machine-readable character data.
Font Fix (callas software) uses the professional callas pdfToolbox engine and handles a broader range of structural font failures including missing font embeddings, CID errors, encoding table failures, and glyph structure problems. It also supports PDF/A compliance in addition to PDF/UA.
If your documents fail validation due to Unicode mapping gaps only, Font Fix (PDFix) is sufficient. If your validation reports missing embeddings, CID errors, or encoding failures, Font Fix (callas software) is the appropriate tool. For the most complex documents, running both actions in sequence is also a valid approach.
