Structured Web Scraper
Turns messy, inconsistent pages into clean, typed data.
Overview
A scraping toolkit that pulls structured records out of pages that never look the same twice, forces them into a known shape, and exports clean data. It's polite enough to run at scale without getting the source site upset.
The problem
A lot of useful data is stuck in HTML that changes from page to page. A naive scraper gives you dirty, inconsistent output, and it gets blocked or throttled before long.
What I needed was something that pulls the data reliably, checks it, and behaves itself against the sites it reads.
The solution
The scraper pairs solid extraction with schema validation. Every record gets coerced into a known shape, and anything that fails validation is set aside rather than quietly corrupting the dataset.
The requests are rate-limited with backoff and jitter, they respect robots directives, and the whole thing caches hard to keep the load off the source.
Architecture
A fetch layer that's polite about rate limits feeds an extractor and a validator. Clean records get exported, and the bad ones are quarantined.
- Schema validation with bad records quarantined, not merged in
- Rate limiting with backoff and jitter
- Caching to keep the load off the source
- Typed output that downstream code can rely on
Screens & diagrams
Key features
Typed output
Records get coerced to a schema, so whatever reads them can trust the shape.
Quarantine, not corruption
Records that don't validate get set aside for a look, instead of polluting the results.
Polite by default
Rate limiting, backoff, and caching keep it a good web citizen.
Easy to point at new sites
A new source is a bit of config and some field mappings.
Implementation highlights
- Made extraction schema-first, so dirty input never becomes dirty output.
- Added rate limiting with backoff and jitter to avoid blocks and go easy on the source.
- Put in a caching layer that cut the repeat requests right down.
Challenges solved
Markup that won't sit still
Field mapping plus validation absorbed the page-to-page variation without me writing brittle selectors.
Not getting blocked
Throttling, backoff, and caching kept the runs sustainable over time.
Technologies
Future improvements
- Work out the extraction schema automatically
- Scheduled incremental crawls that only grab what changed