[postio]
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v1.4·Now with email + phone validation

Blazing fast
Address APIs.

UK address, email & phone validation. One flat price per request. No tiers. No contracts. Prepay with any card.

Get an API key Read the docs
100 FREE LOOKUPSNO CONTRACTS99.99% SLA
GET/address/search
● READY
?q=
Built for edge performance
THREE APIS

All the UK data you'll ever validate.

GET /address

Address lookup

Full UK PAF coverage — 30M addresses. Postcode in, structured address out. Royal Mail synced nightly.

Read docs
GET /email

Email validation

Syntax, MX records, SMTP handshake, and disposable detection. Includes typo suggestions (gmial → gmail).

Read docs
GET /phone

Phone validation

UK mobile, landline, and VoIP detection with carrier lookup. Normalises to E.164 — or rejects.

Read docs
PERFORMANCE

Measured, not claimed.

Every request we served in the last 24 hours. Updated daily.

P50 LATENCY
33ms
P95 LATENCY
291ms
SUCCESS RATE
100%
STATUS
OPERATIONAL
INTEGRATE IN MINUTES

Four lines. Any language.

The API is plain REST. Official SDKs for the languages that want one — everything else works with fetch.

API reference Quickstart 
# Plain REST. One header — x-api-key.
curl 'https://api.postio.co.uk/v1/address/postcode/W1G8YW'  \
  -H "x-api-key: $POSTIO_KEY"
INTEGRATIONS

Drop it in wherever you already work.

SDKs for every major language. A WordPress plugin covering WooCommerce checkout and the major form builders. An MCP server for AI coding agents. Our collection on the Postman Public API Network.

WordPress
Shopify
WooCommerce
Zapier
Node.js
Python
PHP
Laravel
Ruby
Go
Postman
cURL
See all integrations
PRICING

One rate per service. All customers.

Pay only for what you use. No tiers, no minimums, no annual contract.

Address
2.2p/ request
Official Royal Mail PAF Provider
Email
1.0p/ request
Syntax + MX + SMTP Probe
Phone
1.0p/ request
Syntax + Carrier HLR
Start free — 100 lookups on us
  • 100 free lookups
  • No card required
  • No contracts
  • Cancel any time

Trust and compliance

UK data residency

Hosted in London. Address & email stay in the UK; phone checks use an EU carrier network.

GDPR-compliant

Query PII obfuscated after 30 days, configurable per key. DPA available.

Royal Mail PAF

Licensed Royal Mail PAF Solutions Provider. Synced nightly, always current.

99.99% SLA

If we miss it — we credit your balance pro-rata.

Trusted by teams shipping to UK customers.

We dropped our previous address lookup for Postio in an afternoon. Customer drop-off at checkout fell, the API is fast, and the price is honest.

lovebird.co.uk

It's a single script tag. We rolled Postio into three client sites in a week — none of them needed us to touch the form code beyond the snippet.

bigg.co.uk

The data is what we expected. The bit that genuinely surprised us was the support — replies in hours, not days, from someone who actually knew the answer.

xota.co.uk
FAQ

Common questions.

Pricing & billing

Top up your Postio balance with any card from £10. Each request is debited as it happens — the per-request rate is in the pricing section above. Auto-top-up keeps you running when the balance gets low. No invoices, no chasing — just a running balance, like AWS or OpenAI.

Data & security

Reliability & performance

Address, email & phone

Ready in under a minute.

Sign up, grab a key, paste it in. Your first hundred lookups are on us.

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