Address Validation APIs (2026): 10 Options by Country

A wrong flat number or a missing postcode doesn't look like much on a form, but it turns into a returned parcel, a failed delivery or a letter that never arrives. Address validation fixes that at the source, usually with autocomplete as the customer types and a check against official postal data before the order goes through.

This list covers validation and verification, not maps or turning addresses into coordinates. The ten APIs below are listed alphabetically and in no particular order, and every description comes from each provider's own website or documentation, read as of Oct 2026. If you need coordinates for mapping or routing, my guide to geocoding APIs covers that job.

Address validation APIs and the markets they cover

I checked the free plan column on each vendor's own website, as of Oct 2026. Yes means the page names a free plan, a free version or an open source edition. Trial only means the page names a time-limited free trial. Not stated means the page I read named neither, so check the vendor's own site before you sign up.

Tool	Type	Good for	Free plan
EasyPost	Shipping platform with an address verification API	Catching bad addresses before a parcel ships	Not stated
Fetchify	UK address and data validation	Postcode lookup plus email, phone and bank checks	Trial only
getAddress	Australian address API	Autocomplete and look-ups backed by G-NAF	Not stated
Google Address Validation API	Address validation in Google Maps Platform	Validating, standardising and geocoding in one call	Not stated
Ideal Postcodes	UK address validation and postcode lookup	PAF-verified addresses with UPRN and rooftop geocodes	Trial only
Lob	Direct mail platform with address verification	Clean addresses before a direct mail send	Not stated
Loqate	Global address capture and verification	Addresses in 250 countries and territories	Trial only
Melissa	US and international address verification	Change-of-address records and data quality	Not stated
PostGrid	Address verification plus print and mail API	CASS and SERP certified verification	Not stated
Smarty	USPS and international address verification	Parsing, standardising and autocomplete at speed	Not stated

Ten address validation APIs for checkout, mail and data cleaning

EasyPost

Best for: Shippers who want address checks inside the same platform they use for shipping, so errors get corrected at checkout before a parcel leaves.

Fetchify

Best for: UK online shops wanting search-as-you-type address lookup from four characters, plus email, phone and bank account validation and ecommerce plugins.

getAddress

Best for: Australian businesses wanting as-you-type autocomplete and full address look-ups backed by G-NAF, plus ABN and ACN business search and spreadsheet cleaning.

Google Address Validation API

Best for: Developers already on Google Maps Platform who want to validate an address, standardise it for mailing and get its best known geocode.

Ideal Postcodes

Best for: UK teams wanting PAF-verified address lookup with rooftop geocodes and UPRN included, plus an Excel add-in that cleans a column of messy addresses.

Lob

Best for: Marketers sending direct mail who want verification built into the mail platform, so failed deliveries are caught before anything is printed.

Loqate

Best for: Businesses capturing addresses in many countries, with coverage across 250 countries and territories in 78 languages and a 45-day free trial.

Melissa

Best for: US organisations needing global address verification plus change-of-address records, including a GovCloud address suite for government work.

PostGrid

Best for: Teams wanting CASS and SERP certified verification that standardises addresses to local postal rules in real time, alongside a print and mail API.

Smarty

Best for: Developers wanting to verify, parse, standardise, enrich, geocode and autocomplete US and international addresses, starting with 1,000 free lookups.

Two brand names, one address product

Here's the thing I'd want every buyer to know. When the pages were read for this list, the Loqate and Addressy addresses opened the same page, so they're one product under two names. Don't shortlist both and think you've compared two vendors.

Bad addresses are more common than most shops assume. Lob's own page says 20% of addresses entered online contain mistakes, and another provider here says up to 20% of packages run into delivery issues because of bad address data. Even if your own share is lower, every failed delivery means a re-ship and an unhappy customer.

Global coverage or a single-country address specialist

• One country. If you only sell in the UK or Australia, a local specialist built on the national address file, PAF in the UK and G-NAF in Australia, can give richer results such as property references and business numbers.
• Many countries. If you ship worldwide, you need coverage across every market you sell in, in local languages and address formats.
• US mail. If you send a lot of US post, look for CASS certification and USPS data.
• Mail or parcels. Some APIs here sit inside direct mail or shipping platforms. If you already send through one, its built-in verification may be enough.

If you're still choosing how to ship, my roundup of shipping software for small businesses covers the label and carrier side.

What to test during an address API trial

1. Accuracy on your real addresses. Run a sample of past orders, including the messy ones, and see how many get corrected or flagged.
2. Autocomplete speed. How many characters does a shopper type on a phone before useful suggestions appear?
3. Coverage. Does it handle flats, rural addresses and new-build streets in your main markets?
4. Extras. Do you need geocodes, property references, or email and phone checks from the same provider?
5. Integration. Is there a plugin for your shop platform, or will your developers build against the API?

Do you make an address validation API? Tool makers can ask to be considered for a featured place on this list.

My plain advice on choosing an address validation API

Start with where your customers live. If it's one country, test the local specialist against a global provider on a few hundred of your own past orders, and keep whichever corrects more of them. If you sell everywhere, go global and check coverage in your top markets by hand.

Put validation at the point of entry, on the checkout or sign-up form, rather than cleaning records later. It's far easier to fix an address while the customer's still there.

Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.

Frequently asked questions

What does an address validation API do?

It checks an address against official postal data, corrects and standardises it, and tells you whether it's deliverable, usually with autocomplete as the user types.

Is address validation the same as geocoding?

No. Validation confirms an address is real and correctly formatted. Geocoding turns an address into map coordinates. Some providers do both.

What is CASS certification?

It's a USPS certification for software that standardises and checks US addresses. If you send a lot of US mail, look for it.

What is PAF?

PAF is the UK's official postal address file, and several UK lookup services verify addresses against it.

Can I clean an existing address list?

Yes. Several providers here clean whole lists or spreadsheets, not just single addresses at checkout, including add-ins that work inside Excel.