Hosted Scraping Api

---
name: hosted-scraping-api
description: Using managed crawl/scrape/extract APIs — when to outsource scraping and how to evaluate providers — vendor-neutral patterns.
category: web-data
---

## Overview

Managed scraping APIs handle the painful parts of web extraction for you:
headless browsers at scale, proxy rotation, CAPTCHA solving, JavaScript
rendering, and structured extraction — behind a simple HTTP API. You trade
per-request cost for zero infrastructure. This skill covers when that trade
makes sense and how to use such services well, without depending on any
single vendor.

## When to use

- Deciding between self-hosted scraping and a managed API
- Evaluating scraping-API providers (features, pricing, reliability)
- Designing extraction schemas for structured output
- Handling large crawl jobs (sitemaps, batch URLs, webhooks)
- Managing cost and rate limits on pay-per-request scraping

## Core concepts

**The build-vs-buy line.** Self-hosting wins for: high volume on few stable
sites, simple static pages, and tight cost control. Managed APIs win for:
many diverse sites, heavy JavaScript/anti-bot protection, bursty workloads,
and teams without scraping expertise. Estimate honestly — anti-bot evasion
done yourself is a full-time job.

**Capability checklist for providers.** JavaScript rendering, proxy
geolocation and rotation, session/cookie persistence, screenshot/PDF
capture, structured extraction (CSS selectors → JSON, or AI extraction),
crawl (follow links, sitemap handling), webhooks for async jobs, and
compliance posture (how they handle robots.txt, rate limiting, data
retention). Match the checklist to your actual needs — don't pay for
features you won't use.

**Extraction schemas beat raw HTML.** Define the fields you want (title,
price, availability…) and let the API return structured JSON — or post-
process HTML yourself if you need full control. Schema-based extraction is
more resilient to minor site changes than positional scraping, but validate
output like any scraper (sites change; schemas silently empty out).

**Async for scale.** Single-URL sync calls suit interactive use; bulk jobs
(thousands of URLs) go async: submit batch → webhook/poll for completion →
collect results. Design your pipeline around job IDs, retries for failed
URLs, and idempotent result ingestion.

**Cost control is architecture.** Pay-per-request pricing punishes waste:
dedupe URLs before submitting, cache results (respecting freshness needs),
extract only what you need, and set spend alerts/quotas. A runaway crawl
loop is the fastest way to a shocking invoice.

## Practical workflow

1. **Define requirements:** target sites, volume, freshness, JS-heaviness,
   geo needs, and output schema — this determines provider fit and cost.
2. **Evaluate 2–3 providers** with a trial on your hardest 50 URLs:
   success rate, data quality, latency, and actual cost per successful
   extraction (not per requested).
3. **Design the pipeline:** URL discovery/dedup → submit (sync or batch) →
   validate structured output → store with provenance (URL, timestamp,
   provider, job ID) → retry failures with backoff.
4. **Validate relentlessly:** schema checks per result (required fields,
   types, sane ranges), success-rate monitoring, and alerts on drops —
   provider-side changes break extraction too.
5. **Control cost:** caching layer, URL dedup, spend alerts, per-job
   budgets, and periodic "is this still worth it vs self-hosting?"
   reviews as volume grows.
6. **Stay compliant:** confirm the provider's practices align with your
   obligations (robots.txt handling, PII in extracted data, data retention);
   your legal responsibility doesn't outsource with the API call.

## Common pitfalls

- **No output validation** — trusting provider JSON blindly; sites change,
  fields go null, and nobody notices for weeks.
- **Cost surprises** — retries, duplicates, and overly broad crawls
  multiplying per-request charges; budget and alert from day one.
- **Vendor lock-in by accident** — extraction logic written against one
  provider's response format; keep a thin adapter layer so providers are
  swappable.
- **Ignoring the ToS question** — a managed API doesn't absolve you of the
  target site's terms; the compliance decision is still yours.
- **Synchronous calls for bulk work** — timeouts and serial latency;
  use async batch APIs for anything beyond dozens of URLs.
- **Storing provider credentials carelessly** — API keys with scraping
  spend attached are valuable; vault them, scope them, rotate them.