ipapi.co vs Postcodes.io

ipapi.co geolocates an IP address and returns the result as JSON, XML, or YAML without requiring an API key for light use, though the no-key path is rate-limited and marketed by the vendor as a free trial rather than a permanent free tier. Paid subscriptions start at $15/month (or $12/month billed annually) for 60,000 lookups/month, scaling up to $399/month for 15 million/month.

Postcodes.io is a free, open-source (MIT-licensed) UK postcode lookup and geocoding API: it validates postcodes, reverse-geocodes coordinates to the nearest postcode, and returns administrative geography — ward, constituency, parish, LSOA/MSOA, and more — sourced from the ONS Postcode Directory. It's built and maintained by Ideal Postcodes as a free public service, with a paid Ideal Postcodes product available for teams needing rooftop-level precision or fresher data.