Ideal Postcodes API
★ Only Publicly Available OpenAPI DocumentData EnrichmentAddress ValidationapiKey26 EndpointsREST
For Agents
Look up UK and international addresses by postcode, autocomplete partial input, validate emails and phone numbers, and audit per-key lookup usage.
Use for: Look up the addresses at a UK postcode, Autocomplete a partial UK street address as the user types, Validate that a customer's email address is deliverable, Cleanse a free-text address into a standardised PAF record
Not supported: Does not handle parcel rate calculation, postage label generation, or geocoding - use for UK and international address lookup, autocomplete, and validation only.
Jentic publishes the only available OpenAPI specification for Ideal Postcodes API, keeping it validated and agent-ready. Ideal Postcodes provides UK and international address lookup, autocomplete, and validation built on Royal Mail's Postcode Address File. The 26-endpoint API covers postcode-to-address resolution, type-as-you-go autocomplete, address cleansing, and email and phone validation, plus account management for keys, licensees, configs, and lookup history. Integrations rate-limit at 30 requests per second per IP and apply a per-key daily lookup ceiling tied to subscription. The community key 'iddqd' is provided for low-volume testing without onboarding.
Install Jentic One Beta
Connect the Ideal Postcodes API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Ideal Postcodes API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
1
Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fideal-postcodes.co.uk%2Fideal-postcodes" | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fideal-postcodes.co.uk%2Fideal-postcodes" | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
Capabilities
What an agent can do with Ideal Postcodes API.
Resolve a UK postcode to a full set of deliverable addresses via /postcodes endpoints
Autocomplete a typed address fragment for UK or USA via /autocomplete/addresses/{address}/{country}
Cleanse and standardise a free-text address against the Royal Mail PAF via /cleanse/addresses
Validate an email address through /emails for delivery-risk scoring
Validate a phone number through /phone_numbers for line type and country
Manage API keys, configs, licensees, and per-key lookup history through /keys/{key} routes
Audit lookup usage through /keys/{key}/usage and /keys/{key}/lookups for billing and compliance
Use Cases
Patterns agents use Ideal Postcodes API for, with concrete tasks.
★ Checkout Address Autocomplete
Reduce checkout abandonment by autocompleting addresses as customers type. The /autocomplete/addresses/{address}/gbr endpoint returns ranked suggestions in tens of milliseconds, then a single /addresses lookup resolves the chosen suggestion into a complete deliverable record. Integrations are typically live within a day because the autocomplete and lookup pair maps directly onto a standard checkout flow.
Call GET /autocomplete/addresses/{partial}/gbr for each keystroke, then on selection GET /addresses to resolve the full record
Address Cleansing for CRM Imports
When importing leads or customers from a CSV, run each free-text address through /cleanse/addresses to produce a standardised PAF record with UDPRN. This avoids duplicate records and makes downstream geocoding and routing reliable. The endpoint returns confidence scores so agents can flag low-confidence rows for human review.
POST /cleanse/addresses with each row's free-text address and store the returned UDPRN and confidence score on the CRM record
Pre-Send Email Validation
Before sending a transactional email, call /emails to confirm the address syntax and domain look deliverable. The endpoint returns a verdict and risk indicators so an agent can route low-risk addresses straight to send and quarantine high-risk ones for review or fallback channels.
Call GET /emails with the recipient address and only proceed with send when the response indicates a low-risk verdict
AI Agent Onboarding Assistant
An onboarding agent uses Jentic to find Ideal Postcodes operations matching 'validate UK address', autocompletes the user's input, resolves the chosen suggestion, and validates phone and email - all in a single conversational turn. The agent removes the need for the user to fill multiple form fields manually.
Use Jentic search 'validate UK address' to load the Ideal Postcodes /addresses schema and execute it with the postcode the user provided
Key Endpoints
26 endpoints — jentic publishes the only available openapi specification for ideal postcodes api, keeping it validated and agent-ready.
METHOD
PATH
DESCRIPTION
GET
/addresses
Look up addresses by postcode or query
GET
/autocomplete/addresses
Autocomplete address suggestions
GET
/autocomplete/addresses/{address}/gbr
UK address autocomplete
GET
/autocomplete/addresses/{address}/usa
USA address autocomplete
POST
/cleanse/addresses
Cleanse a free-text address into a PAF record
GET
/emails
Validate an email address
GET
/phone_numbers
Validate a phone number
GET
/keys/{key}/usage
Retrieve API key usage statistics
GET
/addresses
Look up addresses by postcode or query
GET
/autocomplete/addresses
Autocomplete address suggestions
GET
/autocomplete/addresses/{address}/gbr
UK address autocomplete
GET
/autocomplete/addresses/{address}/usa
USA address autocomplete
POST
/cleanse/addresses
Cleanse a free-text address into a PAF record
GET
/emails
Validate an email address
GET
/phone_numbers
Validate a phone number
GET
/keys/{key}/usage
Retrieve API key usage statistics
Why Jentic?
What agents get from Jentic-routed access to this vendor.
Setup
Wiring the Ideal Postcodes API by hand means passing your key to authenticate address, email, and phone lookups and mapping its autocomplete and cleanse routes yourself. Through Jentic you install once, import the Ideal Postcodes API from the API Directory, store the API key once, and your agent calls it.
Permission scoping
Ideal Postcodes takes the address query in query and body parameters rather than a resource path, so limit the agent to the operations it needs, such as address lookup, autocomplete, and validation. You choose that allowed set, so email or phone lookups are not included unless you add those operations.
Credential isolation
Your Ideal Postcodes API key is stored once, encrypted, by your own Jentic One instance and injected at execution time. It never enters the agent's prompt, logs, or context.
Intent-based discovery
Agents search Jentic by intent such as 'autocomplete a UK address' or 'validate a postcode', and Jentic returns the matching Ideal Postcodes operation with its input schema so the agent calls the right endpoint without browsing the reference docs.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using Ideal Postcodes API through Jentic.
Why is there no official OpenAPI spec for Ideal Postcodes API?
Ideal Postcodes does not publish an OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call Ideal Postcodes API via structured tooling. It is validated against the live API and kept up to date. Get started with Jentic One, the self-hosted execution layer.
What authentication does the Ideal Postcodes API use?
The Ideal Postcodes API uses an API key passed either as the api_key query parameter or in the Authorization header using the api_key="..." scheme. Through Jentic, the key is stored encrypted in your Jentic One instance and injected at execution time. A community key 'iddqd' exists for low-volume testing with a 15 lookups per IP per day cap.
Can I autocomplete UK addresses with the Ideal Postcodes API?
Yes. GET /autocomplete/addresses/{partial}/gbr returns ranked address suggestions for a partial input string, designed to fire on every keystroke during a UK checkout. After the user selects a suggestion, call GET /addresses to resolve the full deliverable record.
What are the rate limits for the Ideal Postcodes API?
Each IP address is rate limited at 30 requests per second; tripping the limit returns a 503. The autocomplete endpoint has an additional rate limit and per-key daily lookup ceilings tied to your subscription. Build agents to back off on 503 and to batch where possible - for high-volume lookups contact Ideal Postcodes for a higher-limit endpoint.
How do I look up a UK postcode through Jentic?
Run pip install jentic and import the SDK, then await client.search('validate UK address') to find the Ideal Postcodes /addresses operation. Load the schema and execute with the postcode parameter to receive every deliverable address. Run Jentic One, the self-hosted execution layer, for an API key.
Is the Ideal Postcodes API free?
The community key 'iddqd' allows free trial use with a 15 lookups per IP per day limit. Production usage is paid per lookup with subscription tiers - pricing is on the Ideal Postcodes website. The OpenAPI spec describes only the request and response shapes; pricing is account-level.
Can the API cleanse a messy free-text address?
Yes. POST /cleanse/addresses accepts a free-text address and returns a standardised PAF record with UDPRN, confidence score, and component fields. This is the recommended endpoint for CSV imports because it both validates and normalises in a single call.
Can I limit what my agent is allowed to do with the Ideal Postcodes API?
Yes. Because you run Jentic One yourself, you decide which Ideal Postcodes operations the agent may call, so you can allow only address lookup via GET /addresses and autocomplete via GET /autocomplete/addresses/{address}/gbr while leaving out others. The API takes its query in query and body parameters rather than a resource path, so scoping is enforced at the operation level you permit, meaning email validation through GET /emails or phone validation through GET /phone_numbers is excluded unless you explicitly add those operations. Your API key is stored encrypted by your own instance and injected only for the operations you have allowed.
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