I'm curious about the trade-offs mentioned in the comments regarding Unicode handling. For document analysis pipelines (like extracting text from technical documentation or research papers), robust Unicode support is often critical.
Would be interesting to see benchmarks on different PDF types - academic papers with equations, scanned documents with OCR layers, and complex layouts with tables. Performance can vary wildly depending on the document structure.
74910,74912c187768,187779
< [Example 1: If you want to use the code conversion facetcodecvt_utf8to output tocouta UTF-8 multibyte sequence
< corresponding to a wide string, but you don't want to alter the locale forcout, you can write something like:\237 D.27.21954
\251ISO/IECN4950wstring_convert<std::codecvt_utf8<wchar_t>> myconv;
< std::string mbstring = myconv.to_bytes\050L"Hello\134n"\051;
---
>
> [Example 1: If you want to use the code conversion facet codecvt_utf8 to output to cout a UTF-8 multibyte sequence
> corresponding to a wide string, but you don’t want to alter the locale for cout, you can write something like:
>
> § D.27.2
> 1954
>
> © ISO/IEC
> N4950
>
> wstring_convert<std::codecvt_utf8<wchar_t>> myconv;
> std::string mbstring = myconv.to_bytes(L"Hello\n");
01F9020101FC020401F9020301FB02070205020800030209020701FF01F90203020901F9012D020A0201020101FF01FB01FE0208
0200012E0219021802160218013202120222 0209021D0212021D012E013202200222000301FA021A0220021C022002160213012E0222000F000301F90206012C
020301FF02000205020101FC020901F90003020001F9020701F9020E020802000205020A
01FC028C0213021B022002230221021800030200012E021902180216021201320221021A012E00030209021D0212021D012E013202200222000301FA021A0220021C022002160213012E0222000F000301F90206012C
0200020D02030208020901F90203020901FF0203020502080003012B020001F9012B020001F901FA0205020A01FD01FE0208
020201300132012E012F021A012F0210021B013202200221012E0222 0209021D0212021D012E013202200222000301FA021A0220021C022002160213012E0222000F000301F90206012C
~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 <2s.
Why it's fast:
- 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)a better speed comparison would either be multi-process pdfium (since pdfium was forked from foxit before multi-thread support, you can't thread it), multi-threaded foxit, or something like syncfusion (which is quite fast and supports multiple threads). Or even single thread pdfium vs single thread your-code.
These were always the fastest/best options. I can (and do) achieve 41k pages/sec or better on these options.
The other thing it doesn't appear you mention is whether you handle putting the words in reading order (IE how they appear on the page), or only stream order (which varies in its relation to apperance order) .
If it's only stream order, sure, that's really fast to do. But also not anywhere near as helpful as reading order, which is what other text-extraction engines do.
Looking at the code, it looks like the code to do reading order exists, but is not what is being benchmarked or used by default?
If so, this is really comparing apples and oranges.
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.
I haven't tested without SIMD.
Are you using LLMs for parts of the coding?
What's your work flow when approaching a new project like this?
I can't talk about the code, but the readme and commit messages are most likely LLM-generated.
And when you take into account that the first commit happened just three hours ago, it feels like the entire project has been vibe coded.
2. Be not good at or a fan of git when committing
Not sure what the disconnect is.
Now if it were vibecoded, I wouldn't be surprised. But benefit of the doubt
I don't particularly care, though, and I'm more positive about LLMs than negative even if I don't (yet?) use them very much. I think it's hilarious that a few people asked for Python bindings and then bam, done, and one person is like "..wha?" Yes, LLMs can do that sort of grunt work now! How cool, if kind of pointless. Couldn't the cycles have just been spent on trying to make muPDF better? Though I see they're in C and AGPL, I suppose either is motivation enough to do a rewrite instead. (This is MIT Licensed though it's still unclear to me how 100% or even large-% vibe-coded code deserves any copyright protection, I think all such should generally be under the Unlicense/public domain.)
If the intent of "benefit of the doubt" is to reduce people having a freak out over anyone who dares use these tools, I get that.
I'll try my best to make it a really good one!
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 would be good too
also, added python bindings.
as others have commented, I think while this is a nice portfolio piece, I would worry about its longevity as a vibe coded project
Contrasted with python, which is interpreted, has a clunky runtime, minimal optimizations, and all sorts of choices that result in slow, redundant, and also slow, performance.
The price for performance is safety checks, redundancy, how badly wrong things can go, and so on.
A good compromise is luajit - you get some of the same aggressive optimizations, but in an interpreted language, with better-than-c performance but interpreted language convenience, access to low level things that can explode just as spectacularly as with zig or c, but also a beautiful language.
It may be easier to write code that runs faster in Zig than in C under similar build optimization levels, because writing high performance C code looks a lot like writing idiomatic Zig code. The Zig standard library offers a lot of structures like hash maps, SIMD primitives, and allocators with different performance characteristics to better fit a given use-case. C application code often skips on these things simply because it is a lot more friction to do in C than in Zig.
machine code, not https://en.wikipedia.org/wiki/Bytecode
> The price for performance is safety checks
In Zig, non-ReleaseFast build modes have significant safety checks.
> luajit ... with better-than-c performance
No.
Don't disagree but in specific case, per the author, project was made via Claude Code. Although could as well be that Zig is better as LLM target. Noticed many new vibe projects decide to use Zig as target.
- commit message: LLM-generated.
- README: LLM-generated.
I'm not convinced that projects vibe coded over the evening deserve the HN front page…
Edit: and of course the author's blog is also full of AI slop…
2026 hasn't even started I already hate it.
~/c/t/s/zpdf (main)> zig version
0.15.2
If it's really better than what we had before, what does it matter how it was made? It's literally hacked together with the tools of the day (LLMs) isn't that the very hacker ethos? Patching stuff together that works in a new and useful way.
5x speed improvements on pdf text extraction might be great for some applications I'm not aware of, I wouldn't just dismiss it out of hand because the author used $robot to write the code.
Presumably the thought to make the thing in the first place and decide what features to add and not add was more important than how the code is generated?