alt.hn

3/26/2026 at 3:55:52 AM

Show HN: Robust LLM extractor for websites in TypeScript

 https://github.com/lightfeed/extractor

by andrew_zhong

3/26/2026 at 6:53:41 PM

[Update] I will replace the stealth browser with plain playwright and remove anti-bot as a feature.

by andrew_zhong

3/26/2026 at 4:57:01 AM

> Avoid detection with built-in anti-bot patches and proxy configuration for reliable web scraping.

And it doesn't care about robots.txt.

by plastic041

3/26/2026 at 6:01:54 AM

Good point. The anti-bot patches here (via Patchright) are about preventing the browser from being detected as automated — things like CDP leak fixes so Cloudflare doesn't block you mid-session. It's not about bypassing access restrictions.

Our main use case is retail price monitoring — comparing publicly listed product prices across e-commerce sites, which is pretty standard in the industry. But fair point, we should make that clearer in the README.

by andrew_zhong

3/26/2026 at 7:14:43 AM

Regardless. You should still respect robots.txt..

by zendist

3/26/2026 at 7:27:07 AM

We do respect robots.txt production - also scraping browser providers like BrightData enforces that.

I will add a PR to enforce robots.txt before the actual scraping.

by andrew_zhong

3/26/2026 at 7:54:35 AM

How can people believe that you are respecting bot detection in production when your software's README says it can "Avoid detection with built-in anti-bot patches"?

by plastic041

3/26/2026 at 6:54:35 PM

I hear you loud and clear - will replace the stealth browser with plain playwright and remove anti-bot as a feature.

by andrew_zhong

3/26/2026 at 6:36:53 AM

> It's not about bypassing access restrictions.

Yes. It is. You've just made an arbitrary choice not to define it as such.

by messe

3/26/2026 at 7:31:53 AM

I will add a PR to enforce robots.txt before the actual scraping.

by andrew_zhong

3/26/2026 at 5:43:07 AM

> LLMs return malformed JSON more often than you'd expect, especially with nested arrays and complex schemas. One bad bracket and your pipeline crashes.

This might be one reason why Claude Code uses XML for tool calling: repeating the tag name in the closing bracket helps it keep track of where it is during inference, so it is less error prone.

by sheept

3/26/2026 at 2:20:56 PM

Unless I'm totally misunderstanding something it's not xml but special tokens for the tokenizer someone smarter than me might know https://medium.com/@nisarg.nargund/why-special-tokens-matter...

by olafura

3/26/2026 at 6:52:54 PM

Not in Claude Code, where asking it to print the XML used for tool calling makes it accidentally trigger the tool call

by sheept

3/26/2026 at 6:03:52 AM

Yeah that's a good observation. XML's closing tags give the model structural anchors during generation — it knows where it is in the nesting. JSON doesn't have that, so the deeper the nesting the more likely the model loses track of brackets.

We see this especially with arrays of objects where each object has optional nested fields. For complex nested objects, the model can get all items well formatted but one with an invalid field of wrong type. That's why we put effort into the repair/recovery/sanitization layer — validate field-by-field and keep what's valid rather than throwing everything out.

by andrew_zhong

3/26/2026 at 9:02:13 AM

Hardly matters, this isn't a problem that you'd have these days with modern LLMs.

Also, a model can always use a proxy to turn your tool calls into XML

And feed you back json right away and you wouldn't even know if any transformation did take place.

by faangguyindia

3/26/2026 at 9:37:25 AM

We do see fewer invalid JSONs on latest bigger LLMs but still can happen on smaller and cheaper models. There is also case when input is truncated or a required field not found, which are inherently difficult.

On XML vs JSON, I think the goal here is to generate typed output where JSON with zod shines - for example the result can type check and be inserted to database typed columns later

by andrew_zhong

3/26/2026 at 9:48:39 AM

Thing is even with XML LLM will fail every now and then.

I've built an agent in both tool calling and by parsing XML

You always need a self correcting loop built in, if you are editing a file with LLM you need provide hints so LLM gets it right the second time or 3rd or n time.

Just by switching to XML you'll not get that.

I used to use XML now i only use it for examples in in system prompt for model to learn. That's all

by faangguyindia

3/26/2026 at 9:57:26 AM

Agreed - in this project I did a one path sanitation to recover invalid optional / nullable fields or discard invalid objects in nested array.

I know multi path LLM approaches exist: e.g. generating JSON patches

https://github.com/hinthornw/trustcall

by andrew_zhong

3/26/2026 at 6:12:27 AM

[dead]

by AbanoubRodolf

3/26/2026 at 5:09:13 AM

This looks pretty interesting! I haven't used it yet, but looked through the code a bit, it looks like it uses turndown to convert the html to markdown first, then it passes that to the LLM so assuming that's a huge reduction in tokens by preprocessing. Do you have any data on how often this can cause issues? ie tables or other information being lost?

Then langchain and structured schemas for the output along w/ a specific system prompt for the LLM. Do you know which open source models work best or do you just use gemini in production?

Also, looking at the docs, Gemini 2.5 flash is getting deprecated by June 17th https://ai.google.dev/gemini-api/docs/deprecations#gemini-2.... (I keep getting emails from Google about it), so might want to update that to Gemini 3 Flash in the examples.

by Flux159

3/26/2026 at 8:45:10 AM

HTML -> markdown -> LLM is standard practice. We strip elements like aside, embed, head , iframe etc. the criteria is conservatively set to avoid removing too many elements (especially in extractMain mode)

https://github.com/lightfeed/extractor/blob/main/src/convert...

I have used gemma 3 and had good results.

Once Gemini 3 flash drops the preview suffix, will update the examples. Thank you for the pointer.

by andrew_zhong

3/26/2026 at 12:10:07 PM

Would this work for my use case?

I need to extract article content, determine it's sentiment towards a keyword and output a simple json with article name, url, sentiment and some text around the found keyword.

Currently I'm having problems with the json output, it's not reliable enough and produces a lot of false json.

by l3x4ur1n

3/26/2026 at 3:22:12 PM

What kind of LLMs are you using? In structured output mode?

In this library we recover nullable and optional fields, invalid elements in nested array, bad urls, repair incomplete JSONs. If these issues are what you see, yes it should work for your case.

by andrew_zhong

3/26/2026 at 7:57:03 AM

The extraction prompt would need some hardening against prompt injection, as far as i can tell.

by letier

3/26/2026 at 9:11:25 AM

My instinct was also to use LLMs for this, but it was way to slow and still expensive if you want to scrape millions of pages.

by vetler

3/26/2026 at 10:06:09 AM

Put things to perspective - Gemini 2.5 flash is 0.3/1M tokens - assuming each page is 700 tokens and output is not much you are looking at $210 for 1M pages

by andrew_zhong

3/26/2026 at 11:54:00 AM

You will absolutely struggle to get all the info you need into 700 tokens per page.

Edit: There's also the added complexity of running a browser against 1M pages, or more.

by vetler

3/26/2026 at 3:26:08 PM

I agree that When pages have similar structure, for one time extraction as it is (not reasoning from context), scraping with selectors is the way to go.

This library also supports HTML as input so running a browser is not required.

by andrew_zhong

3/26/2026 at 5:57:10 AM

What's your experience with not getting blocked by anti-bot systems? I see you've custom patches for that.

by dmos62

3/26/2026 at 6:21:00 AM

The anti-bot patches here (via Patchright) are about preventing the browser from being detected as automated — fixing CDP leaks, removing automation flags, etc. For sites behind Cloudflare or Datadome, that alone usually isn't enough — you'll need residential proxies and proper browser fingerprints on top. The library supports connecting to remote scraping browsers via WebSocket and proxy configuration for those cases.

by andrew_zhong

3/26/2026 at 9:27:35 AM

As someone who is getting HAMMERED TO NO BELIEVE by residential proxies, I just want to express my hatred to all of you.

by spiderfarmer

3/26/2026 at 9:36:44 AM

My platform has 24M pages on 8 domains and these NASTY crawlers insist on visiting every single one of them. For every 1 real visitor there are at least 300 requests from residential proxies. And that's after I blocked complete countries like Russia, China, Taiwan and Singapore.

Even Cloudflares bot filter only blocks some of them.

I'm using honeypot URLs right now to block all crawlers that ignore rel="nofollow", but they appear to have many millions of devices. I wouldn't be surprised if there are a gazillion residential routers, webcams and phones that are hacked to function as a simple doorways.

Things are really getting out of hand.

by spiderfarmer

3/26/2026 at 1:45:49 PM

What crawlers are using residential proxies?

by cj

3/26/2026 at 2:12:58 PM

Now if they identified themselves, I could block them.

I'd put my money on Chinese AI model makers, but I don't trust any company that is in desperate need of fresh data.

by spiderfarmer

3/26/2026 at 6:39:37 AM

This feels like slop to me.

It may or may not be, but if you want people to actually use this product I’d suggest improving your documentation and replies here to not look like raw Claude output.

I also doubt the premise that about malformed JSON. I have never encountered anything like what you are describing with structured outputs.

by AirMax98

3/26/2026 at 8:01:03 AM

In context of e-commerce web extraction, invalid JSON can occur especially in edge cases, for example:

price: z.number().optional() -> price: “n/a”

url: z.string().url().nullable() -> url: “not found”

It can also be one invalid object (e.g. missing required field, truncated input) in an array causing the entire output to fail.

The unique contribution here is we can recover invalid nullable or optional field, and also remove invalid nested objects in an array.

by andrew_zhong