API Changelog
Subscribe to statutory rate changes and platform releases. For programmatic notifications, see Real-time Webhooks.
October 1, 2026 — v1.2.0
v1.2.0 — Statutory Quarterly Release
Statutory Rate Enactments
- Warren County Permissive Levy: Effective October 1, 2026, Warren County permissive sales tax increased by 0.50%, raising the total combined statutory rate from 6.75% to 7.25%.
New Platform Capabilities
- US Census Street Geocoding: Added full address-level resolution via
?address=...matching against US Census Bureau TIGER/Line polygons. - Structured Ambiguous ZIP Resolution: Over 530 multi-county Ohio ZIP codes now return structured candidate counties with individual rates and FIPS codes.
- Sliding-Window Rate Limiter: Enforced 10 req/s sliding window with RFC-standard
X-RateLimit-*andRetry-Afterheaders. - HMAC-SHA256 Webhooks: Real-time push notifications for
rate.changed,rate.announced, andcertificate.expiring.
July 1, 2026 — v1.1.0
v1.1.0 — Performance & Caching Release
- RFC 7807 Problem Details: Standardized all error payloads with canonical problem details schemas (
title,status,detail,request_id). - Transit Authority Decompositions: Added explicit breakdown for COTA, WRTA, and Laketran levies.
January 1, 2026 — v1.0.0
v1.0.0 — Initial Public Release
- Initial public release of Ohio Rate-Lookup API across all 88 Ohio counties.
- Statutory origin-sourcing compliance under Ohio Revised Code § 5739.033(B)(1).
- Unmetered public catalog endpoint at
/api/v1/counties.