What is a semantic index in web scraping?
TL;DR
A semantic index stores previously scraped content. Cached pages return in milliseconds instead of seconds.
What is a semantic index?
When you request a page that's been scraped before, the index returns stored data immediately rather than re-crawling. This reduces latency dramatically.
| Metric | Live Scrape | Cached |
|---|---|---|
| Latency | 2-10 seconds | 50-200ms |
| Cost | Full crawl | Reduced |
| Availability | Site dependent | Always |
Why it matters
- AI agents: Real-time decisions need instant data access
- User apps: Sub-second response times required
- High volume: Cache hits reduce costs and time
Firecrawl's maxAge parameter lets you specify acceptable cache age—instant results when fresh data exists.
Key Takeaways
Semantic indexing delivers cached data in milliseconds, essential for real-time AI applications.
Last updated: Jan 26, 2026