Data Sources & Methodology

How we collect, index, and display Chicago building information.

Data sources

• Chicago Building Code Violations. Published by the Chicago Department of Buildings via the Chicago Data Portal (dataset 22u3-xenr). The city updates it daily; we re-ingest nightly.

Additional sources (311 complaints, Cook County Assessor ownership, Cook County Recorder LLC ownership chains) are planned for future releases.

How addresses are matched

Every address is normalized to a join key (uppercase, punctuation stripped, USPS-style abbreviations: STREET → ST, NORTH → N, etc.). The same building always maps to the same key regardless of how you type it.

If a search returns "no data," the address as typed may not match the city's records exactly. Try common variations (with/without directional, "St" vs "Street").

What we do not show

• No tenant-side eviction data. Under the Illinois Eviction Sealing Act (2022), sealed eviction records cannot be used for tenant screening. When eviction data is added in the future, it will be aggregated by landlord only.
• No free-text user reviews. The current product surfaces public records only. Reviews and user accounts are out of scope for this release.

Corrections & takedown requests

If you believe information shown about a property is inaccurate, or you have a takedown request, email joe@jzimmermanco.com. We'll respond within a week and correct or remove the record if warranted.

Caveats

• Data is provided as-is, sourced from public records. We don't independently verify each row.
• A violation on record doesn't necessarily mean current non-compliance. Many are routine and resolved quickly. Look at the status field.
• Backfill coverage is being expanded; older violations may not yet be indexed.