Today's Deep-Dive: Crawl4AI
Ep. 278

Today's Deep-Dive: Crawl4AI

Episode description

Crawl4AI is a rebellious open-source web crawler designed to transform the chaotic internet into clean, structured data suitable for large-language models (LLMs). It addresses the problem of messy web data that wastes LLM tokens and yields poor results, especially for AI applications like retrieval-augmented generation. The crawler’s core philosophy is to be LLM-friendly, outputting clean, LLM-ready markdown that retains structure while removing HTML and CSS boilerplate. Developed out of frustration with existing closed-source and expensive tools, Crawl4AI emphasizes affordability and accessibility. Its technical strengths include speed and control, achieved through an async browser pool and full browser control using the Chrome developer tools protocol to handle JavaScript and dynamic content. The tool also features a “stealth mode” to bypass bot detection, balancing resource usage with effectiveness. Intelligence is key, with “fit markdown” using heuristic filtering to automatically remove useless page elements, significantly reducing token counts and improving AI accuracy. For targeted crawls, it employs the BM 25 algorithm to ensure relevance, and “adaptive crawling” uses information foraging to learn site structure and stop when enough relevant information is gathered. Crawl4AI also offers revolutionary LLM table extraction, intelligently chunking large tables to overcome memory limits. Deployment is straightforward with a simple Python install and a robust Docker setup for production, including API requests, security, and cloud deployment. Recent updates include webhooks for real-time notifications and retry logic, simplifying integration. The project’s mission is to foster a transparent data economy, keeping the core project free and independent through a tiered sponsorship program. Future developments include an agentic crawler for autonomous multi-step data tasks, prompting further thought on how AI might redefine research processes.

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0:00

Welcome to the deep dive where we cut through the noise to give you the essentials

0:04

fast today

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we're getting stuck into something really interesting actually a

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Pretty rebellious open source project shaking things up in the AI data world. We're

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talking about crawl for AI. It's a web crawler

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Yes, but it's specifically designed to take the wealth the chaos of the internet

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and turn it into clean structured data that large-language models

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Can actually use so our mission today?

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Simple we're gonna unpack tech docs the github buzz. I mean this thing has over

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fifty five thousand stars

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It's the most popular crawler out there right now and figure out what problem it

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really solves and importantly how its whole approach is built

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around LLMs

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We want this to be a really clear starting point for you, even if you're just

0:42

dipping your toes into modern data pipelines

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But before we dive in a quick shout out to our supporter for this deep dive safe

0:48

server safe server helps with hosting powerful software

0:50

Like crawl for AI and can really support your digital transformation. You can find

0:54

out more at www.safe-server.de

0:57

Okay, let's set the scene if you're building anything with AI today, especially

1:01

stuff like Argo retrieval augmented generation

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Right where the model needs to pull in outside info. Exactly. You hit this wall.

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Immediately. The web is just messy for machines

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Anyway, it's full of junk menus ads footers all that boilerplate feed that raw

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stuff to an LLM

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You're wasting tokens like crazy and well the answers you get back are great. That

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really is the heart of the problem

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It's not just about grabbing data anymore. It's about cleaning it structuring it as

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you grab it

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And that's where crawl for AI came from. It's open source a crawler and scraper

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Yeah, but its main job its whole philosophy is being LLM friendly

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The key output the revolutionary bit is that it turns the web into clean LLM ready

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markdown markdown

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That's the magic ingredient, isn't it? It's simple keeps the structure

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You know headers lists but ditches all the messy HTML and CSS that just inflates

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token counts and confuses the AI

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Precisely and the backstories kind of amazing actually

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Yeah, pure developer frustration really the founder who has a background in NLP

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was trying to scale up data gathering back in 2023 and

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Found the existing tools were just lacking

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They were either closed source and expensive or they pretended to be open source

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But then you needed accounts API tokens. Sometimes they were hidden fees

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It felt like a lock-in right blocking affordable access to do serious work. So what

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happened sounds like someone got pretty fired up

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Oh, yeah, he literally said he went into turbo anger mode. This wasn't some big

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corporate project. It was personal

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He built crawl for AI fast put it out there as open source for availability

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Meaning anyone could just grab it no strings attached with the goal of affordability

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The whole idea is democratizing knowledge making sure a structured text images

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metadata all prep for AI

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Isn't stuck on a paywall. Okay, that explains the massive github following that

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drive for openness

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But you know developers need tools that actually work not just ones with a good

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story

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So let's shift gears. What are the technical chops that make this thing stand out?

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Speed and control seem to be big selling points. Definitely performance and control

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are paramount

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They call it fast in practice and that comes down to smart design choices

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Like it uses an async browser pool for anyone new to that async just means it doesn't

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do things one by one

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It juggles hundreds of browser requests at the same time

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This cuts down waiting time uses your hardware way more efficiently, right?

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That makes sense a big efficiency boost right there

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But the web fights back doesn't it sites use JavaScript load things late and they're

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actively trying to block bots

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How does crawl for AI handle that minefield? That's where full browser control

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comes in. It's not pretending to be a browser

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It's actually driving real browser instances. It uses something called the Chrome

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developer tools protocol

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So it sees the page exactly like you would it runs the JavaScript waits for stuff

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to load in

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Handles those images that only appear when you scroll down lazy loading

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Okay, and it can even simulate scrolling down the page what they call full page

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scanning to grab content on those infinite scroll sites

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Okay, that's clever, but let's talk bot detection. That's the big headache for many

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people right? Yeah, you mentioned stealth mode

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Sounds great, but doesn't running a full browser trying to look human make

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everything much slower and heavier

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What's the real-world trade-off there for getting past Cloudflare or Akamai? That's

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a fair question. Absolutely

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There's always a trade-off running a full browser is more resource intensive than a

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simple request no doubt

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but crawl for AI tries to balance that with the async stuff and smart caching we

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mentioned and

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Honestly the benefit of stealth mode which uses configurations to mimic a real user

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Often outweighs the cost because the alternative is just getting blocked

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Failing the crawl completely plus it handles the practical things you need like

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using proxies managing sessions

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So you can stay logged in keeping cookies persistent if you need to scrape behind a

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login got it, so it's fast

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It's sneaky when it needs to be and it really controls the browser environment now

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Let's get to the AI part of crawl for AI the output is AI friendly clear

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But how does the crawler itself use intelligence not just to grab stuff, but to

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filter it maybe even learn this feels like the core innovation

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Yeah, this is where you see features really tailored for optimizing tokens and

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boosting our each performance

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It starts with how it generates the markdown

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You've got your basic clean markdown which just strips out the obvious HTML junk,

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right?

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But then there's fit markdown this uses heuristic based filtering. Okay heuristic

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filtering

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Can you break that down a bit for someone new to this?

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What does that actually mean for the data they get sure?

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Think of heuristics as smart rules of thumb

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The crawler uses these rules to guess what parts of a web page are probably useless

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You know navigation menus sidebars footers

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Maybe comment sections fit markdown tries to identify and just delete that stuff

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automatically

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Imagine cutting say 40% of the useless words the tokens from a page just by being

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smart about removing the boilerplate

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That saves you real money on LLM calls

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But more importantly, it makes your area G system way more accurate because the AI

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is only looking at the actual content the important stuff

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Right efficiency through intelligence makes sense. What if I have a really specific

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goal?

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Like I only want the q4 earnings numbers from a company site. How does it filter

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out all the other noise?

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For that kind of targeted crawl it can use the BM 25 algorithm. Yeah, I'm 20

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Yeah, it's a well-known ranking function from information retrieval

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Basically think of it as a sophisticated way to score how relevant a piece of text

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is to your specific search query

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So if you tell the crawler you're looking for

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q4

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2024 earnings report BM 25 helps ensure the final markdown focuses tightly on text

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related to those terms

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It helps ignore the CEOs blog post or the company picnic photos

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Okay. Now this is where it gets really cutting-edge based on the source docs

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adaptive crawling

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My understanding is this helps the crawler know when it's found enough information

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like when to stop

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Spot-on and that's huge for saving resources old-school crawlers

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Just follow links deeper and deeper until they hit some arbitrary limit super wasteful

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adaptive crawling is smarter

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It uses these advanced information forging algorithms fancy term that basically the

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crawler learns the site structure as it goes

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It's constantly asking is the new information I'm finding actually relevant to the

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original query

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Yeah, and it figures out when it's gathered enough information to likely answer

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that query based on a confidence level you can set

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So instead of blindly following 50 links and maybe only 10 were useful it might

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stop after 15 because it thinks okay

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I probably got what I need exactly that you set a threshold it hits it and that

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specific crawl job shuts down

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It's optimizing based on knowledge gathering not just link counting very smart

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efficiency and intelligence working together. Okay one more intelligence piece

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Structured data tables are vital right for databases training models, but huge

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tables can crash scrapers

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Yeah, memory limits are a classic problem crawl for AI tackles this with what they

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call

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Revolutionary LLM table extraction you can still use the old way CSS selectors XPath

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But it can also use LLMs directly for pulling out table data

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The clever part is intelligent chunking instead of trying to load a massive multi-page

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table into memory all at once which often fails

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It breaks the table into smaller manageable pieces

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uses the LLM to process each chunk extract the data clean it up and then stitches

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the results back together seamlessly it's built for

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Handling really big data sets that covers the what and how brilliantly so last

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piece deployment

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How easy is it for say a developer or a small team to actually get this thing

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running and plugged into their workflow?

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Well, the basic install is super easy if you use Python just pip install that you

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crawl for I standard stuff

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But they clearly built it knowing that real world large-scale use needs more than

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just running it on your laptop

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Which naturally leads to their docker setup. I imagine exactly the Docker I set up

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is really key for production

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It bundles everything up neatly you get a ready-to-go fast PI server for handling

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API requests is built in security with JWT tokens

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And it's designed to be deployed in the cloud and handle lots of crawl jobs

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Simultaneously and I saw something crucial in the latest updates webhooks that

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feels like a major quality of life improvement

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Right. No more constantly checking if a job is done

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Oh, absolutely gets rid of that tedious polling process the recent version added a

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full webhook system for the Docker job queue API

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So yeah, no more polling is the headline there crawl for AI can now actively tell

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your other systems

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When a crawl job is finished or when an LLM extraction task is complete. It sends

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out real-time notifications

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They even built in retry logic. So if you're receiving system hiccups, it won't

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just fail

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It makes integration much smoother that really brings it all together. Doesn't it

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back to that original mission building an independent powerful tool?

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That's genuinely accessible. They didn't just build a better crawler. They build a

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whole transparent ecosystem for getting data

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Absolutely. Yeah, their mission is clear about that

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Fostering a shared data economy making sure AI gets fed by real human knowledge

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staying transparent that tiered sponsorship program

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They have is specifically to keep the core project free and independent true to

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that original rebellion against walled gardens

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It really is a great summary of crawl for AI then a powerful open source way to

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bridge the gap between the messy web

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And what modern AI actually needs structured clean data driven by speed control and

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that really smart adaptive intelligence

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But you know this space never stands still looking at their roadmap

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They've got some fascinating ideas cooking things like an agentic crawler right

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like an autonomous system that could handle complex

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Multistep data tasks on its own and a knowledge optimal crawler

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It makes you wonder and here's a final thought for you our listener to chew on if a

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crawler can learn when to stop because it's

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Satisfied an information need what other boundaries will AI start redefining and

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how we find and use data

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Could we see AI systems soon that just autonomously manage the entire research

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process from asking the question

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To delivering a structured report something to think about. Okay. Let's thank our

10:58

supporter one last time safe server

11:00

Remember they help with hosting and support your digital transformation. Check them

11:03

out at

11:04

www.safeserver.de

11:06

Happy crawling

11:06

Happy crawling