Address Parser API: What It Returns, Compared
Live responses from three messy US addresses, our published accuracy numbers, and five address-parsing options side by side, with vendor details checked October 5, 2026.
An address parser API takes one line of address text and returns its parts as separate fields: house number, street name, street type, direction, unit, city, state, ZIP and ZIP+4. Some parsers also standardize casing, correct typos and report how confident they are in the result. Parsing splits an address into fields. Checking deliverability against postal data is a separate step, called verification.
What a parser returns: three messy inputs, live
We sent three badly typed US addresses to the sthan.io parser on October 4, 2026. Each column is one live call. The field names are the ones the API returns.
| Field | Input 1 | Input 2 | Input 3 |
|---|---|---|---|
| Typed as | 1600 pensylvania avenu nw washngton dc | Seattle WA 98109 400 Broad St | 233 south wacker drive suite3300 chicago illinois |
| What is wrong with it | Three typos, no commas, no ZIP | City, state and ZIP typed first | Suite glued to its number, state spelled out, no ZIP |
| addressNumber | 1600 | 400 | 233 |
| streetPreDir | null | null | S |
| streetName | Pennsylvania | Broad | Wacker |
| streetPostType | Ave | St | Dr |
| streetPostDir | NW | null | null |
| unitType / unitNumber | null | null | null (suite not confirmed) |
| city | Washington | Seattle | Chicago |
| stateCode | DC | WA | IL |
| zipCode | 20500 | 98109 | 60606 |
| zip4 | 0005 | 4607 | 7147 |
| matchTier | Near | Exact | Near |
| confidence | 0.9 | 1 | 0.9 |
| matchCode (what changed) | street Corrected; city, ZIP and ZIP+4 Inferred | ZIP+4 Inferred | unit Unmatched; ZIP and ZIP+4 Inferred |
Three things stand out. First, the typos in input 1 were fixed, and the response says so: the street is marked Corrected and the tier drops from Exact to Near. Second, the reordered input 2 came back Exact, because the parts were all right, only in the wrong order. Third, the parser could not confirm suite 3300 from input 3. It returned the building, marked the unit Unmatched and kept the tier at Near. If the unit matters to you, read the unit match code before you store the result.
The same building with the suite written as "Suite 3300" and the ZIP included, sent to the sthan.io verification endpoint, came back as 233 S Wacker Dr STE 3300, Chicago, IL 60606-6387 with deliverableStatus Confirmed. That is the job of verification; see cleansing vs verification vs standardization.
How accurate is parsing on messy input?
One example proves little. In August 2026 we ran the sthan.io parser on 26,943 corrupted versions of real, verified US addresses, sent to the live parser in its maximum-recovery mode. These are the published results:
| Metric | Result |
|---|---|
| Corrupted inputs tested (all verified real addresses) | 26,943 |
| Recovered: formatting-only corruption (casing, separators, whitespace) | 99.9% |
| Recovered: single-field damage (a typo, a dropped field) | 96.2% |
| Recovered: structural damage (reordered fields, multiple errors) | 89.7% |
| Recovered: compound damage (several severe corruptions at once) | 71.2% |
| Recovered: average across all severities | 88.5% |
| Wrong answer with no warning | at most 0.14% (about 1 in 700); wrong state: zero |
| Wrong answer, but flagged as uncertain | 3.4% |
| Returned nothing instead of guessing | 7.9% |
The row to watch is the silent one: a wrong answer with no warning happened on at most 0.14% of inputs. Everything else that was wrong came back flagged or empty. The method and examples are in the US address parser accuracy benchmark, so you can run the same test on any vendor.
Address parsing options compared, October 6, 2026
We read each vendor's own documentation on October 4, 2026, and rechecked prices on October 5, 2026. The fields shown are taken from each vendor's documentation; long field lists are shortened.
| API | What it is | Fields it returns (from its docs) | Free | Paid entry price |
|---|---|---|---|---|
| sthan.io US Address Parser | US parser | addressNumber, streetPreDir, streetName, streetPostType, streetPostDir, unitType, unitNumber, city, stateCode, zipCode, zip4, plus matchTier, confidence, matchCode | 100 a month, 10 a minute, no card | $8 a month for 10,000 |
| Smarty US Street Address API and US Extract API | US verification API that returns components; Extract finds and validates US addresses inside full-text strings | components: primary_number, street_name, street_suffix, city_name, state_abbreviation, zipcode, plus4_code and more | 42-day trial, 1,000 lookups, no card | Annual plans: $195 a year for 12,000 lookups, or $552 a year for 60,000 |
| PostGrid parse endpoint | Part of its address verification API: "Break an address apart into its components" | houseNumber, road, unit, level, poBox, postcode, city, state, country and more | 500 free credits | Essential: $18/month billed yearly, or $20/month billed monthly, for 2,000 lookups |
| Interzoid Address Parse | Parser for US and global addresses | StreetNumber, PreDirection, StreetName, StreetSuffix, PostDirection, UnitType, UnitNumber, City, StateProvince, PostalCode, Country | Free trial credits for new accounts, usable on any Interzoid API; the amount is not stated (no free plan on its pricing page) | $20 a month for 1,000 credits |
| APIVerve Street Address Parser | US street address parser | streetNumber, streetType, streetAddress, cityName, stateName, zipCode | 200 credits a month, non-commercial use, attribution required | $29.99 a month for 200,000 credits; a parse costs 2 credits, so about 100,000 parses (our math) |
Three differences matter more than price. Signals: sthan.io's response carries a confidence score and a per-field match code; Smarty's sample adds an analysis block with delivery-point (DPV) codes and footnotes; the Interzoid, APIVerve and PostGrid samples return the fields and a status. Units: APIVerve's documented response example does not show a unit field. Credits: Interzoid says one credit equals one API call except for premium APIs. APIVerve's Street Address Parser costs two credits per call, so its 200,000-credit Starter plan covers about 100,000 parses.
Open-source parsing libraries are another route. You run them on your own servers and keep them up to date yourself.
Geocoders parse too, but answer a different question
Geocoding APIs also split addresses into parts. Geocodio says address parsing and standardization is automatically included with all forward geocoding lookups, with 2,500 free lookups a day and $1 per 1,000 after that. Geoapify's Geocoding API returns the parsed query (housenumber, street, postcode, city, state) next to the coordinates, and its free plan gives 3,000 credits a day. Both are geocoders: their main output is a point on the map. They are a good fit if you need coordinates anyway. If you need postal fields and a signal of what was corrected, compare the parser APIs above.
Which one fits
| You need | Look at |
|---|---|
| Split typed US addresses into database columns, with a flag when something was corrected | sthan.io US Address Parser |
| Find addresses inside emails, documents or web pages | Smarty US Extract API |
| Parse addresses outside the US | Interzoid Address Parse, which supports global addresses |
| Parsed fields plus a postal deliverability status | A verification API that returns components, such as Smarty US Street or sthan.io verification |
| Coordinates as well as fields | A geocoder, such as Geocodio or Geoapify |
Where sthan.io fits. The sthan.io US Address Parser returns the fields above, plus a match tier, a confidence score and a per-field match code with each successful match. The free tier is 100 parses a month (10 a minute) with no credit card. Paid plans start at $8 a month for 10,000. If you also need to know an address is deliverable, sthan.io verification starts at $12 a month for 10,000, after 100 free a month. sthan.io is not CASS-certified.
Frequently Asked Questions
Sources
Live sthan.io API responses, benchmark results and product details read October 4, 2026; vendor pricing rechecked October 5, 2026 (APIVerve credits per parse and the Interzoid trial on October 6, 2026): sthan.io/pricing/united-states; smarty.com/pricing/us-address-verification and smarty.com/blog/monthly-vs-annual-plans-how-to-choose; smarty.com/docs/apis/us-extract-api/reference; avdocs.postgrid.com (Parse an Address) and postgrid.com/pricing-address-verification; interzoid.com/apis/address-parse, interzoid.com/pricing and interzoid.com/getting-started-apis; docs.apiverve.com/ref/streetaddressparser, docs.apiverve.com/api-endpoints, apiverve.com/marketplace/streetaddressparser and apiverve.com/pricing; geocod.io/guides/address-parsing and geocod.io/pricing; apidocs.geoapify.com/docs/geocoding/forward-geocoding and geoapify.com/pricing. Prices change; check the vendor page before you buy.
Parse 100 US addresses a month free
No credit card. Each successful match includes a match tier, a confidence score and what was corrected.