ArcGIS Location Platform vs OpenCage Geocoding API

ArcGIS Location Platform

Per-unit prices are public for every service, with a monthly free tier of 20,000 geocodes and 20,000 routes, keys limited to chosen privileges and a 99.9 per cent SLA. No rate limits or OpenAPI description were found, results may not be stored unless the dearer stored geocode is bought, and the agreement bars benchmarking without written permission.

OpenCage Geocoding API

Permanent storage of results on every plan, including after you cancel. Geocoding only, no place search or routing.

ArcGIS Location Platform

1. Send the token in an X-Esri-Authorization: Bearer or Authorization header. The docs' examples put it in a token parameter, which Esri's own best-practice page calls less secure.
2. Set forStorage=true on findAddressCandidates or reverseGeocode only when results will be kept. It needs pay-as-you-go and the Geocode (stored) privilege, and costs eight times the unstored rate.
3. Cap geocoding output with maxLocations (default and maximum 50) and outFields, because billing counts results returned and the default returns every field.
4. Page place searches with pageSize (maximum 20) and offset. A nearby or extent search costs $8 per 1,000 requests after 500 free a month.
5. Check the JSON body for an error object with code, message and details. Code 499 means the token is missing and 403 means it lacks the privilege.

OpenCage Geocoding API

1. Add no_annotations=1 and limit=1 when you only need coordinates
2. Stop on 402, which means the day's quota is gone, and back off on 429
3. Add no_record=1 when the query holds personal data
4. Redact the key parameter before logging request URLs
5. Credit OpenStreetMap wherever you show results