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Base URL

The OMOPHub API is built on REST principles. We enforce HTTPS in every request to improve data security, integrity, and privacy. The API does not support HTTP. All requests contain the following base URL: 
https://api.omophub.com/v1

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Authentication

To authenticate you need to add an Authorization header with the contents of the header being Bearer oh_xxxxxxxxx where oh_xxxxxxxxx is your API Key. 
Authorization: Bearer oh_xxxxxxxxx
Get your API key from the OMOPHub Dashboard

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Core Capabilities

Search & Discovery
  • Search across 90+ medical vocabularies (SNOMED CT, ICD-10-CM, RxNorm, LOINC and more)
  • Fuzzy, semantic, and phonetic search algorithms
  • Autocomplete and suggestions endpoints
Concept Navigation
  • Navigate concept hierarchies and relationships
  • Get ancestors, descendants, and related concepts
  • Explore “Is a”, “Maps to”, and custom relationships
Vocabulary Mapping
  • Map concepts between different vocabulary systems
  • Cross-reference codes across standards
  • Validate and check mapping coverage
OHDSI Compliance
  • Full OMOP CDM vocabulary support (license-free)
  • Standardized concept classifications
  • Version-controlled vocabulary releases

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API Structure

RESTful Design
  • Resource-based endpoints (/concepts, /vocabularies, /search)
  • Standard HTTP methods (GET, POST)
  • Consistent response formats
Field Naming
  • snake_case for all API fields (concept_id, vocabulary_id)
  • Consistent parameter naming across endpoints
Pagination
  • Page-based pagination (page, page_size)
  • Metadata includes total counts and navigation flags

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API Categories

Concepts

Look up medical concepts and their detailed information

Search

Advanced search across vocabularies and concepts

Hierarchy

Navigate concept hierarchies and relationships

Relationships

Explore concept relationships and connections

Domains & Classifications

Work with concept domains and classifications

Mappings

Cross-vocabulary mappings and interoperability

Vocabularies

Manage and explore medical vocabularies and their metadata

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Quick Start Examples

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Search for Medical Concepts

curl -X GET "https://api.omophub.com/v1/search/concepts?query=diabetes&vocabulary_ids=SNOMED&page_size=5" \
  -H "Authorization: Bearer YOUR_API_KEY"

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Get Concept Details

curl -X GET "https://api.omophub.com/v1/concepts/201826" \
  -H "Authorization: Bearer YOUR_API_KEY"

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Map Between Vocabularies

curl -X GET "https://api.omophub.com/v1/concepts/201826/mappings?target_vocabularies=ICD10CM" \
  -H "Authorization: Bearer YOUR_API_KEY"

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Response Format

All API responses follow a consistent structure: 
{
  "success": true,
  "data": {
    // Your response data here
  },
  "meta": {
    "request_id": "req_abc123",
    "timestamp": "2024-01-15T10:30:00Z",
    "vocab_release": "2024.2"
  }
}

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Response codes

Resend uses standard HTTP codes to indicate the success or failure of your requests. In general, 2xx HTTP codes correspond to success, 4xx codes are for user-related failures, and 5xx codes are for infrastructure issues.
StatusDescription
200Successful request.
400Check that the parameters were correct.
401The API key used was missing.
403The API key used was invalid.
404The resource was not found.
429The rate limit was exceeded.
5xxIndicates an error with Resend servers.
Check Error Codes for a comprehensive breakdown of all possible API errors.

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Rate limit

The default maximum rate limit is 2 requests per second. This number can be increased by request. After that, you’ll hit the rate limit and receive a 429 response error code. Learn more about our rate limits.

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Next Steps

Authentication Setup

Configure your API key and start making requests

Interactive API Explorer

Try the API directly in your browser

Vocabulary Versions

Learn about vocabulary releases and versioning

Error Handling

Understand error codes and troubleshooting
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