UK Address API · v1All systems normal

UK addresses,
properly.

Postcode lookup, autocomplete, and distance — in 30ms. Pulled from the Royal Mail PAF every week. Drop the snippet in. You're done.

29Maddresses
1.8Mpostcodes
30msp50 latency
99.99%uptime
30ms p50
postcodesautocompletedistance
// GET /v1/postcodes/{postcode}
$curl https://api.address.st/v1/postcodes/SW1A1AA
{
  "postcode":    "SW1A 1AA",
  "line_1":      "Buckingham Palace",
  "town":        "London",
  "country":     "England",
  "latitude":    51.5014,
  "longitude":   -0.1419
}
⌘ K
SW1A 1AABuckingham Palace, London
live!
Powering checkout & address entry at
NorthwindTesseraGreylock&CoOctaveFoundryHatch
The API

Three endpoints. That's it.

Built deliberately small. Every endpoint is JSON in, JSON out. Versioned, rate-limited per key, edge-served from 300+ locations.

GET/v1/postcodes/{postcode}

Postcode lookup

Resolve any UK postcode to a structured address with coordinates.

GET/v1/autocomplete

Address autocomplete

Type-ahead search ranked by relevance and popularity, not alphabet.

GET/v1/distance

Distance between two postcodes

Great-circle and driving distance, in km or miles, with bearing.

curlnodepythonruby
copy
curl https://api.address.st/v1/postcodes/SW1A1AA \
-H "Authorization: Bearer $ADDRESS_ST_KEY"
Why address.st

The boring, dependable middle.

Not the cheapest. Not the flashiest. The one your team will still be using in five years because it just kept working.

Royal Mail PAF licensed

We pay the licence so you don't have to. Refreshed every Monday morning. Compliant by default — no separate agreements, no quarterly audits.

Updates · weekly

Edge served, 300+ POPs

Cloudflare Workers, deployed where your users are. p50 30ms, p99 under 90ms anywhere in the UK.

p50 · 30ms

One SDK, every stack

TypeScript, Python, Ruby, PHP, Go, .NET. Thin wrappers around one REST API. No magic.

v1 · stable

Built for production

Per-key rate limits, audit logs, IP and domain restrictions, webhooks for usage thresholds. Boring, in a good way.

SOC 2 · in progress

29M addresses, 1.8M postcodes

Every BFPO, every multi-occupancy. We carry the long tail so you don't get angry support tickets.

Coverage · 100% UK

Pay how it makes sense

Monthly subscriptions for steady traffic. Top-up credits for the occasional spike. Switch any time, no notice.

Billing · monthly or top-up
Try it

Two postcodes in. Distance out.

Great-circle by default. Driving distance behind a flag. Perfect for delivery zones, store finders, and rate-card calculators.

A
B
SW1A 1AAEH1 1YZM1 1AEBS1 4STL1 8JQEC4M 8AD
// resolved
Buckingham Palace, London
Royal Mile, Edinburgh
GET /v1/distance200 OK · 28ms
Great-circle
533.6km
Miles
331.6mi
AB
bearing 339°
N ↑
Live status

99.99% over the last 90 days.

Two regions, automatic failover, public status page. We pay our SLA credits in the next billing cycle if we miss.

p50
28ms
p99
86ms
incidents
0
90 days ago6030today
What it's good for

Drop it into anything that asks for a UK address.

Not opinionated. Not a platform. Just one fast, accurate source of truth for UK addresses, hooked up to whatever you're shipping.

Checkout

Cut shipping address entry to two fields. Watch your conversion go up.

Store finders

Resolve a postcode, sort branches by distance. Done in an afternoon.

Delivery zones

Reject out-of-range postcodes before the user hits pay.

Analytics

Roll up customers by town, region, or coordinate. Real geography, not regex on postcodes.

Pricing

Pay monthly, or top up credits.

Subscriptions for steady traffic. Pay-as-you-go credits for the occasional spike. Cancel any time. No annual contracts.

Hobby

Free1,000 calls / mo

For weekend projects and proof-of-concepts. No card needed.

  • All three endpoints
  • Community Discord
  • 1 API key
Most popular

Starter

£12/ month

For real apps with steady traffic. Pays for itself if it saves an hour.

  • 50,000 calls / mo
  • Email support, 1-day
  • 5 API keys
  • Domain & IP restrictions
  • Audit logs

Pro

£49/ month

For teams shipping at scale. Add top-up credits for spikes.

  • 500,000 calls / mo
  • Priority support, 2-hour
  • Unlimited keys
  • SOC 2 reports
  • Top-up credits, no expiry
  • 99.99% SLA with credits
Need more? Talk to us about Enterprise · Volume discounts from 2M calls / mo.
Questions, mostly

The things people ask before signing up.

Don't see yours? Email us — a real human reads the inbox.

Where does the data come from?

Royal Mail's Postcode Address File (PAF). We pay the licence and refresh every Monday morning. You're getting the same source the post office uses.

Is there a free tier?

Yes — 1,000 calls a month, every endpoint, no card required. Upgrade when you need to. No usage cliffs, no surprise emails.

How fast is it really?

p50 around 28ms, p99 under 90ms, anywhere in the UK. Edge-served from 300+ Cloudflare locations. We publish live latency on the status page.

What happens if I exceed my plan?

We don't cut you off. Calls keep working, billed at the overage rate (£0.002 per call on Starter, £0.001 on Pro). You'll get a heads-up email at 80% and 100% of the cap.

Can I restrict which domains can use my key?

Yes, on Starter and up. Set an allow-list of domains and IPs per key. Browser-side keys are signed with a referrer policy automatically.

Do you offer an SLA?

99.99% on Pro, with billing credits if we miss. Hobby and Starter run on the same infrastructure, but the SLA is contractual on Pro and Enterprise.

Ready when you are

Look up your first postcode in 60 seconds.

Sign up, copy your key, paste it into curl. We don't ask for a card until you cross the free tier — and we'll email you before that happens.