Yeah, sorry for confusion. When said Unicode, meant foreign text rather (just) the unescaped symbols, e.g. Greek. At one random Greek textbook[0], zpdf output is (extract | head -15):
Lol, but there's 100 competitors in the PDF text extraction space, some are multi million dollar industries: AWS textract, ABBY PDFreader, PDFBox, I think you may be underestimating the challenge here.
- 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)
What it handles:
- 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)
it allows the program to reference memory without having to manage it in the heap space. it would make the program faster in a memory managed language, otherwise it would reduce the memory footprint consumed by the program.
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
Not being slow - they compile straight to bytecode, they aren't interpreted, and have aggressive, opinionated optimizations baked in by default, so it's even faster than compiled c (under default conditions.)
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.
Zig is safer than C under default conditions, not faster. By default does a lot of illegal behavior safety checking, such as array and slice bounds checking, numeric overflow checking, and invalid union access checking. These features are disabled by certain (non default) build modes, or explicitly disabled at a per scope level.
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.
>you have the time and energy to do stuff like all the bullet points listed
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.
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?
In my experience with parsing PDFs, speed has never been an issue, it has always been a matter of quality.
I tried a small PDF and got a memory error. It's definitely much faster than MuPDF on that file.
fixed.
Yeah, sorry for confusion. When said Unicode, meant foreign text rather (just) the unescaped symbols, e.g. Greek. At one random Greek textbook[0], zpdf output is (extract | head -15):
This for entire book. Mutool extracts the text just fine.[0]: https://repository.kallipos.gr/handle/11419/15087
Lol, but there's 100 competitors in the PDF text extraction space, some are multi million dollar industries: AWS textract, ABBY PDFreader, PDFBox, I think you may be underestimating the challenge here.
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 <2s.
Why it's fast:
What it handles: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.
I have now made parallel by default and added an option to enable multiple threads.
I haven't tested without SIMD.
You've released quite a few projects lately, very impressive.
Are you using LLMs for parts of the coding?
What's your work flow when approaching a new project like this?
Claude Code.
> Are you using LLMs for parts of the coding?
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.
Hard disagree. Initial commit was 6k LOC. Author could've spent years before committing. Ill advised but not impossible.
Why would you make Claude write your commit message for a commit you've spent years working on though?
1. Be not good at or a fan of git when coding
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
What's fast about mmap?
it allows the program to reference memory without having to manage it in the heap space. it would make the program faster in a memory managed language, otherwise it would reduce the memory footprint consumed by the program.
You mean it converts an expression like `buf[i]` into a baroque sequence of CPU exception paths, potentially involving a trap back into the kernel.
What’s the fidelity like compared to tika?
The accuracy difference is marginal (1-2%) but the speed difference is massive.
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 would be good too
added a comparison, will improve further. https://github.com/Lulzx/zpdf?tab=readme-ov-file#comparison-...
also, added python bindings.
thanks, claude, I guess haha
as others have commented, I think while this is a nice portfolio piece, I would worry about its longevity as a vibe coded project
If he made something legitimately useful, who cares how?
Now we just need Python bindings so I can use it in my trash language of choice.
added python bindings!
Were you working on it already, or did it take you less than 17 minutes to commit https://github.com/Lulzx/zpdf/commit/9f5a7b70eb4b53672c0e4d8... ?
excellent stuff what makes zig so fast
Not being slow - they compile straight to bytecode, they aren't interpreted, and have aggressive, opinionated optimizations baked in by default, so it's even faster than compiled c (under default conditions.)
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.
Zig is safer than C under default conditions, not faster. By default does a lot of illegal behavior safety checking, such as array and slice bounds checking, numeric overflow checking, and invalid union access checking. These features are disabled by certain (non default) build modes, or explicitly disabled at a per scope level.
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.
will add this to the list, now learning new languages is less of a barrier with LLMs
It makes your development workflow smooth enough that you have the time and energy to do stuff like all the bullet points listed in https://news.ycombinator.com/item?id=46437289
>you have the time and energy to do stuff like all the bullet points listed
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.
- First commit 3hours ago.
- 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.
Using Ai isn't lazier than your regurgitated dismissal, to be fair.
...and it does not work. I tried it on ~10 random pdfs, including very simple ones (e.g. a hello world from typst), it segfaults on every single one.
Tried few and works. Maybe you've older or newer Zig version than whatever project targets. (Mine is 0.15.2.)
Wait, but why?
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?