Compare two servers

The compare command fetches two CapabilityStatements and produces a diff report.

Basic usage

fhir-capability-analyzer compare <sourceA> <sourceB>

Each source can be a URL or a local JSON file path, independently:

# Two live servers
fhir-capability-analyzer compare https://server-a.example.com https://server-b.example.com

# Local baseline vs live server
fhir-capability-analyzer compare ./fixtures/baseline.json https://staging.example.com

# Two local files
fhir-capability-analyzer compare ./capability-v1.json ./capability-v2.json

Output formats

Text (default)

fhir-capability-analyzer compare ./examples/hapi-r4.json ./examples/us-core-server.json

Comparison: ./examples/hapi-r4.json → ./examples/us-core-server.json
N difference(s) found

Added in B (N)
...
Removed in B (N)
...
Changed (N)
...

JSON

fhir-capability-analyzer compare a.json b.json --format json

Produces a stable ComparisonReport JSON object with added, removed, and changed arrays.

Markdown

fhir-capability-analyzer compare a.json b.json --format markdown

CI assertion: fail on any difference

fhir-capability-analyzer compare ./baseline.json https://staging.example.com --exit-on-diff

Exit code 1 when any difference is found. Exit code 0 when capabilities match exactly.

What is compared

Category	What is checked
fhir-version	Top-level fhirVersion field
format	Declared content formats (json, xml, etc.)
resource	Which resource types are declared
interaction	Per-resource interactions (read, create, search-type, etc.)
search-param	Per-resource search parameter names
operation	Per-resource and system-level operations
profile	Per-resource profile and supportedProfile URLs
security	CORS and authentication services

Exit codes

See Exit codes.