Stable Address Keys

Every geocoding result from Geocodio includes a stable address key: a unique, persistent identifier for the geocoded address. Think of it as a permanent reference ID that maps back to a specific address in Geocodio's system.

Once you have a stable address key, you can use it to look up the address again later to refresh your data, enrich it with additional data, or deduplicate records.

What is a Stable Address Key?

A stable address key is a unique string that Geocodio assigns to every geocoded address. Stable address keys are included by default with every request. You don’t need to do anything special in order to request them.

Stable address keys look like this:

The key is included automatically in every geocoding response as the stable_address_key column:

For example:

Stable Address Keys and Accuracy Levels

For house number-level results (rooftop, range_interpolation, etc.), the key is unique to a specific house number on a street. For street_center results, the key is unique to a specific street.

A stable address key is provided for rooftop, point, range_interpolation, and street_center accuracy types, but not for place, county, or state -level results.

How Stable Address Keys Work

• Deterministic: The same address always produces the same key, regardless of minor formatting differences. "1109 N Highland St" and "1109 North Highland Street" will return the same stable address key.

• Persistent: A key, once issued, will always remain valid. You can store it and use it to look up the same address months or years later.

• Cross-version: Stable address keys work across all API versions.

• Opaque: Treat the key as one complete string that you can use and store as-is. (Don’t try to parse it.)

Billing

Stable address keys are included for free with all geocoding results.

If you want to refresh your data in the future to see if accuracy has improved for those addresses, you can submit the stable address key on its own. This counts as one geocoding lookup.

If you supply the stable address key with at least one field append, you’ll only pay for the data appends. For example, if you need to refresh your list with the latest Congressional districts, or you forgot to request Census tracts during the initial geocoding, you’ll only pay for the data appends if you supply the stable address keys.

How Stable Address Keys Can Be Used

1. Dedupe Addresses

Two addresses that resolve to the same location will share the same stable address key, even if they're formatted differently. This makes deduplication straightforward: geocode your addresses, then group by stable address key to find duplicates.

For example, all of these produce the same key:

• "1109 N Highland St, Arlington, VA 22201"
• "1109 North Highland Street, Arlington, Virginia 22201"
• "1109 N. Highland St., Arlington VA"

2. Refresh Results with the Latest Data

Geocodio's data coverage improves over time. An address that previously returned a range interpolated result may later be upgraded to a more precise rooftop-level result.

By storing the stable address key, you can re-query the address in the future to get the latest and most accurate geocoding data without needing to keep the original address string.

3. Add Data Appends Without Paying for Geocoding Again

If you've already geocoded an address and stored the key, you can request additional field appends later and the geocoding portion is free. You only pay for the data appends themselves.

4. Use as a Universal Address Identifier

Stable address keys can be used anywhere an address is accepted as input across Geocodio. This includes forward and reverse geocoding, distance calculations, and both our API and spreadsheet upload tool.

Useful Resources

• API Docs – Stable Address Keys
• Geocodio Guides