What Is an AI Web Crawler? Crawler vs Scraper, Explained Simply
People say "AI web crawler" and mean two different things. Mixing them up leads to picking the wrong tool. Here is the short version. Me, the first time someone said "just use an AI crawler": Meaning 1: a bo
People say "AI web crawler" and mean two different things. Mixing them up leads to picking the wrong tool. Here is the short version.
Me, the first time someone said "just use an AI crawler":
Meaning 1: a bot that an AI company runs
OpenAI, Anthropic, Google and Perplexity send bots to read public web pages. If you own a website, these are the bots that visit you. Each company publishes the names:
| Bot | Company | What it is for |
|---|---|---|
| GPTBot | OpenAI | Content that may be used to train models |
| OAI-SearchBot | OpenAI | Search results in ChatGPT |
| ChatGPT-User | OpenAI | A person asked ChatGPT to open a page |
| ClaudeBot | Anthropic | Content that could be used to train models |
| Claude-SearchBot | Anthropic | Better search results |
| Claude-User | Anthropic | A person asked Claude a question |
| PerplexityBot | Perplexity | Search results in Perplexity |
So the bots do three jobs: training, search, and one person's request. You can allow one and refuse another in robots.txt:
User-agent: GPTBot
Disallow: /
User-agent: OAI-SearchBot
Allow: /
Think before you block everything. OpenAI says a site that opts out of OAI-SearchBot will not be shown in ChatGPT search answers.
Meaning 2: a tool that you run
You are building an agent, a chatbot or a RAG pipeline. Your model needs web pages as input. A raw page is full of menus and scripts, so you use a tool that fetches the page and returns clean text, usually Markdown.
These tools do one or both of two jobs. This is the part people mix up.
Crawler vs scraper
A crawler finds pages. You give it one starting address. It follows links and discovers more pages.
A scraper reads pages. You give it an address. It returns what is on that page and goes nowhere else.
| Crawler | Scraper | |
|---|---|---|
| You give it | One starting address | The exact addresses you want |
| It does | Follows links to find pages | Reads each page you named |
| Cost | Hard to know before you start | One request for each page |
| Best for | "Get everything on this site" | "Get these pages" |
Which one do you need?
Ask one question: do you already know the URLs?
- Yes (from a search result, a sitemap, your own list, or a link a user pasted): a scraper is enough.
- No (you only know the site and must find every page): you need a crawler first, then a scraper to read the pages.
If you use a crawler, set a page limit and a depth limit. One site may have 50 pages. The next may have 50,000.
Tools for each job
- Crawling: Firecrawl (hosted), Crawl4AI (open source), and Apify's Website Content Crawler.
- Scraping: Spicrawl, which is what we build. You send a URL, or up to 10,000 in one batch, and get Markdown, JSON, HTML, text or PDF back. It does not crawl. It reads the pages you name.
Reading one page looks like this:
curl https://api.spicrawl.com/v1/scrape \
-H "Authorization: Bearer $SPICRAWL_API_KEY" \
-H "Content-Type: application/json" \
-d '{"url": "https://example.com", "response_format": "markdown"}'
Be a good visitor
- Read
robots.txtand follow it. - Go slowly on small sites.
- Keep a copy, and do not fetch the same page again and again.
- A 403 or a block page is a message. Stop and check.
What a 403 is really saying:
In one line
A crawler finds pages. A scraper reads them. Know which one you mean, and the right tool is easy to pick.
This is a shorter version of a guide on the Spicrawl blog. The full post has every bot, more examples and all the sources: What is an AI web crawler?
Originally published by Dev.to AI. Aggregated on AIWithGhost for educational purposes β full credit and traffic to the original publisher.