---
title: "Seed URL"
slug: seed-url
date: 2026-10-07T08:26:09+00:00
modified: 2026-10-07T08:35:45+00:00
permalink: https://brightdata.com/glossary/seed-url
type: page
---

# Seed URL

**TLDR:** A seed URL is the starting web address a crawler uses to begin discovery. Every other page in a crawl is reached by following links outward from the seeds, so seed selection determines what a crawl can and cannot find.

A **seed URL** is the initial entry point given to a [web crawler](/products/crawl-api) before a crawl begins. The crawler fetches the seed, extracts its links, queues them, and repeats the process outward. A crawl can start from a single seed or from thousands. Pages that cannot be reached by following links from a seed will never be visited, which makes seed selection one of the highest-leverage decisions in any crawl configuration.

### How Seed URLs Work:

1. **Fetch**: The crawler requests the seed URL and retrieves its HTML.
2. **Extract**: All links on the page are pulled out through [link extraction](/glossary/link-extraction) and resolved from relative to absolute form.
3. **Normalize**: Discovered URLs are canonicalized through [URL normalization](/glossary/url-normalization) so duplicate variants collapse into a single entry.
4. **Enqueue**: New URLs are added to the crawl queue, known as the [URL frontier](/glossary/url-frontier).
5. **Repeat**: The crawler pulls the next URL from the queue and continues until the queue empties or a limit such as [crawl depth](/glossary/crawl-depth) is reached.

### Choosing Seed URLs:

Good seeds are link-rich pages that sit close to the content you actually want. A homepage is the obvious default but often a poor choice for targeted crawls, because valuable pages may sit many hops away behind navigation. Category listings, paginated indexes, author archives, and [sitemaps](/glossary/sitemap) usually deliver faster and more complete coverage.

For an e-commerce crawl, seeding from category listing pages reaches product pages in one or two hops instead of four or five from the homepage. For a documentation site, seeding from the table of contents captures nearly every page immediately. When a site publishes a sitemap, using its URLs as seeds bypasses link discovery entirely.

### Seed Strategies Compared:

StrategyTypical hops to targetCoverageBest forHomepage only4–6Broad but shallowSmall sites, full-site discoveryCategory pages1–2TargetedE-commerce, listings, catalogsSitemap URLs0Only what the site publishesLarge sites with maintained sitemapsMulti-seed hybrid0–2HighestProduction crawls at scale### Example Crawl Configuration:

```
{
  "seeds": [
    "https://example.com/products/electronics",
    "https://example.com/products/home-garden",
    "https://example.com/products/clothing"
  ],
  "allowed_domains": ["example.com"],
  "max_depth": 3,
  "exclude_patterns": ["/cart", "/account", "*?sort="]
}
```

Three category seeds replace a single homepage seed. Every product page is reachable within the depth limit, and the exclusion patterns stop the crawler from spending requests on cart, account, and sort-parameter URLs.

### Common Seed Selection Mistakes:

1. **Seeding only the homepage**: Pushes target content beyond the depth limit and burns requests on navigation pages.
2. **Seeding search result URLs**: Query-parameter pages generate near-infinite variations and can trap a crawler in an endless loop.
3. **Ignoring pagination**: A category seed that only reaches page one misses most of the catalog unless pagination links are explicitly followed.
4. **Seeding redirect chains**: Consumes requests and can drop the crawler onto an unintended domain when redirects are not handled.
5. **Seeding without scope rules**: Without [crawl scope](/glossary/crawl-scope) boundaries, outbound links can pull the crawl off-domain entirely.

### Seed URLs at Scale:

At small scale, seed choice affects efficiency. At large scale it determines feasibility. A crawl of millions of pages built from a single seed spends an enormous share of its budget rediscovering the same navigation structures. Distributing thousands of seeds across parallel workers removes most of that redundant fetching, provided a shared frontier prevents two workers from crawling the same URL.

Bright Data’s [Crawl API](/products/crawl-api) accepts single or bulk seed inputs, handles normalization and deduplication automatically, and manages the proxy layer so seeded crawls complete without being blocked mid-run.

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