Question 1

What does the PDF Alt Text Generator do?

Accepted Answer

It loads your PDF in the browser using pdf-lib and walks every page's XObject resources to enumerate all images. For each image it checks whether an /Alt (or /ActualText) entry already exists, then lets you add or override alt text through a pipe-separated textarea (one image per line: page|image_index|alt_text). You can also auto-generate placeholder alt text ('Image N on page M'), mark images without meaningful content as decorative so screen readers skip them, and download the updated PDF. A WCAG 2.1 SC 1.1.1 compliance score is computed based on how many images have alt text.

Question 2

What extra features does this tool have compared to others?

Accepted Answer

(1) Page-range parser (reuse shared module). (2) Image enumerator per page. (3) Pipe-separated alt-text parser. (4) Alt-text applier (sets /Alt entry on image XObject). (5) Decorative-image marker (empty /Alt + artifact). (6) Image list formatter for UI display. (7) Alt-text validator (length, descriptiveness, no-filename-only). (8) Auto-alt-text generator ('Image N on page M'). (9) Missing-alt-text finder. (10) Multi-format renderers (text/CSV/JSON). (11) Copy + Download. (12) History (localStorage, last 20). (13) Shareable URL. (14) Summary stats (total images, with alt, without alt, decorative count). (15) Alt-text quality scorer. (16) Image type detector (photo/diagram/chart/decorative heuristic). (17) WCAG 2.1 compliance checker. (18) Page-by-page image count.

Question 3

How does the decorative-image marker work?

Accepted Answer

When you mark an image as decorative, the tool sets its /Alt entry to an empty string and adds an /Artifact flag (PDF/UA convention). Screen readers conforming to PDF/UA will skip these images entirely. This is the WCAG 2.1 technique for purely decorative images that convey no information (borders, background patterns, spacer GIFs).

Question 4

What format does the alt-text textarea use?

Accepted Answer

One image per line in the format: page|image_index|alt_text. The pipe (|) separates fields; the alt_text field may contain spaces and commas. Lines starting with # are ignored as comments. Whitespace around the alt_text is trimmed. Example: '1|0|Company logo showing blue circle with white checkmark'.

Question 5

Is my data sent anywhere?

Accepted Answer

No. All alt-text processing runs 100% in your browser using JavaScript and pdf-lib. Your PDF never leaves your device, and the tool works offline. History is stored in localStorage on this device only.

PDF Alt Text Generator

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