Zpdf: PDF text extraction in Zig

Post by lulzx » Tue, Dec 30, 2025, 7:57 PM UTC

  - Memory-mapped file I/O (no read syscalls)
  - Zero-copy parsing where possible
  - SIMD-accelerated string search for finding PDF structures
  - Parallel extraction across pages using Zig's thread pool
  - Streaming output (no intermediate allocations for extracted text)

  - XRef tables and streams (PDF 1.5+)
  - Incremental PDF updates (/Prev chain)
  - FlateDecode, ASCII85, LZW, RunLength decompression
  - Font encodings: WinAnsi, MacRoman, ToUnicode CMap
  - CID fonts (Type0, Identity-H/V, UTF-16BE with surrogate pairs)

Post by tveita » Tue, Dec 30, 2025, 9:24 PM UTC

lulzx wrote: post #2

I built a PDF text extraction library in Zig that's significantly faster than MuPDF for text extraction workloads. ~41K pages/sec peak throughput. Key choices: memory-mapped I/O, SIMD string search, parallel page extraction, streaming output. Handles CID fonts, incremental updates, all common compression filters. ~5,000 lines, no dependencies, compiles in Why it's fast: - Memory-mapped file I/O (no read syscalls) - Z…

Post by cheshire_cat » Tue, Dec 30, 2025, 9:28 PM UTC

lulzx wrote: post #2

I built a PDF text extraction library in Zig that's significantly faster than MuPDF for text extraction workloads. ~41K pages/sec peak throughput. Key choices: memory-mapped I/O, SIMD string search, parallel page extraction, streaming output. Handles CID fonts, incremental updates, all common compression filters. ~5,000 lines, no dependencies, compiles in Why it's fast: - Memory-mapped file I/O (no read syscalls) - Z…

Post by lulzx » Tue, Dec 30, 2025, 9:38 PM UTC

tveita wrote: post #4

lulzx wrote: post #2

I built a PDF text extraction library in Zig that's significantly faster than MuPDF for text extraction workloads. ~41K pages/sec peak throughput. Key choices: memory-mapped I/O, SIMD string search, parallel page extraction, streaming output. Handles CID fonts, incremental updates, all common compression filters. ~5,000 lines, no dependencies, compiles in Why it's fast: - Memory-mapped file I/O (no read syscalls) - Z…

What kind of performance are you seeing with/without SIMD enabled? From https://github.com/Lulzx/zpdf/blob/main/src/main.zig it looks like the help text cites an unimplemented "-j" option to enable multiple threads. There is a "--parallel" option, but that is only implemented for the "bench" command.

Post by lulzx » Tue, Dec 30, 2025, 9:55 PM UTC

mpeg wrote: post #5

very nice, it'd be good to see a feature comparison as when I use mupdf it's not really just about speed, but about the level of support of all kinds of obscure pdf features, and good level of accuracy of the built-in algorithms for things like handling two-column pages, identifying paragraphs, etc. the licensing is a huge blocker for using mupdf in non-OSS tools, so it's very nice to see this is MIT python bindings…