Introducing Stable Address Keys: Deduplicate, Refresh, and Enrich Your Address Data for Less

Quick summary: Geocodio now provides a stable address key with every geocoding result, so you can geocode your list of addresses, group by stable address key, and easily surface duplicates.

Anyone who works with address data knows the deduplication problem. The same physical address can appear in a database dozens of different ways.

String matching catches some of these. But abbreviations, punctuation, spacing, and formatting differences make it unreliable at scale. And even after you normalize the addresses, unit numbers are still problematic. It’s tough to say "these are all the same address" at scale even if you’ve built custom matching logic.

To save you from that frustrating process, Geocodio now provides Stable Address Keys: persistent, unique identifiers included in every geocoding result. Geocode your list, group by stable address key, and duplicates will surface instantly.

Stable address keys are also useful for refreshing your data and adding new field appends to previously geocoded addresses. As a bonus, when you use a stored key to request data appends, you only pay for the appends. The geocoding portion is free.

As of API v1.11, stable address keys also support unit-level geocoding for secondary address lines. (apartments, suites, units, and more).

How do stable address keys work?

Every geocoding result from Geocodio now includes a stable_address_key field — a short, unique string that permanently identifies the geocoded address. It looks something like this:

As long as you’re using v1.11 or later, you don't need to change anything about how you use the API or spreadsheet uploader. The key shows up automatically in every response.

We recommend storing your keys alongside your geocoded results so you can use them later.

So,…what can you do with them?

Deduplicate your address lists

The same physical address can appear in your database dozens of different ways:

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

All three of these will produce the exact same stable address key. That's because the key is deterministic — the same address always generates the same key, regardless of formatting differences like abbreviations, punctuation, or spacing.

This greatly simplifies deduplication. Geocode your addresses, then group by stable_address_key. Records that share a key are the same address. No string comparison or other custom matching logic needed.

Re-run addresses for free with data appends

Here's where stable address keys save you money.

Take this example: You geocoded 50,000 addresses last month. Now your team needs Census demographics and Congressional district data appended to those same records.

Without stable address keys, you'd have to re-geocode all 50,000 addresses and pay for both the geocoding and the data appends.

With stable address keys, you only pay for the data appends. Pass the stored key instead of the address, and request the fields you need:

This works the same way in batches. You can even mix regular addresses and stable address keys in the same batch request. The API handles both seamlessly.

Refresh your data with the latest results

Geocodio's data coverage is always improving. An address that returned a range_interpolation result six months ago might now have a precise rooftop match. New data sources are added regularly, parsing is continually refined, and our accuracy improves steadily.

Stable address keys make it easy to take advantage of those improvements. Re-query a stored key at any time to get the most current data from Geocodio for that address.

This is especially useful if you're maintaining a permanent database of geocoded addresses. Instead of periodically re-geocoding your entire dataset from scratch, you can refresh records using their stored keys.

A universal reference for your address data

Beyond deduplication and cost savings, stable address keys work as lightweight, portable identifiers that you can use to link address records across systems. They're accepted anywhere Geocodio takes an address string (forward and reverse geocoding; single geocoding; batch and list geocoding; and distance calculations) in our API and spreadsheet upload tool.

For spreadsheet users, just look for the "Geocodio Stable Address Key" column in your geocoded spreadsheet downloads.

A few things to know:

• Keys are persistent: A key issued today will still work months and years from now.
• Keys work across API versions: You can store a key from v1.10 and use it with future versions.
• Keys are available for all supported countries: US, Canada, Mexico, United Kingdom, New Zealand, and Australia.
• New keys may be issued: As Geocodio’s coverage expands, an address that previously returned a street_center-level key may return a more specific house number-level key in the future.

Extending Stable Address Keys for Unit-Level Precision

Geocodio’s stable address keys also support unit-level geocoding for secondary address lines. When a secondary address line is present, a unit suffix is simply appended to the key.

This means every unit gets its own unique, stable identifier. Extended stable address keys work the same as standard address keys. Once you have a unit-extended key, you can use it to look up the address again later.

Billing at a glance

The billing is straightforward. Stable address keys are included for free with all 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 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. This applies to both API usage and spreadsheet uploads.

Getting started

You don’t need to enable or configure anything new. Stable address keys are already included in every geocoding response from the Geocodio API (v1.11+). The single most impactful thing you can do is start storing the stable_address_key alongside your geocoded results. Whenever you need to add data, refresh results, or clean up duplicates down the road, you'll have the keys ready to go.

Check out the full documentation for details on key format, billing, and usage across all API endpoints.

As always, if you have any questions, reach out to our support team. We're always here to help!