Request log and stats

Every imposter records the requests it receives and keeps running statistics. Both are in memory, per imposter.

Request log

curl "http://localhost:2525/imposters/2f334551/requests?limit=2"

[
  {
    "id": "2b19816a-ce7d-47d6-91d2-636ff010de30",
    "imposterId": "2f334551",
    "timestamp": "2026-10-01T21:17:47.547Z",
    "request": {
      "method": "GET",
      "path": "/customers/42",
      "headers": { "accept": "*/*", "host": "localhost:4000", "user-agent": "curl/8.7.1" },
      "query": {},
      "body": null
    },
    "response": {
      "status": 200,
      "headers": { "content-type": "application/json", "x-served-by": "imposters" },
      "body": "{\"path\":\"/customers/42\",\"plan\":\"pro\"}",
      "matchedStubId": "7a1d5d07",
      "proxied": false,
      "outcome": "stub",
      "responseIndex": 0
    },
    "duration": 0
  },
  {
    "id": "315e7518-8da2-4562-8c4d-6a7a412b6a9f",
    "imposterId": "2f334551",
    "timestamp": "2026-10-01T21:17:47.562Z",
    "request": {
      "method": "GET",
      "path": "/refunds",
      "headers": { "accept": "*/*", "host": "localhost:4000", "user-agent": "curl/8.7.1" },
      "query": {},
      "body": null
    },
    "response": {
      "status": 404,
      "headers": { "content-type": "application/json" },
      "body": "{\"error\":\"No matching stub found\",\"method\":\"GET\",\"path\":\"/refunds\"}",
      "proxied": false,
      "outcome": "unmatched"
    },
    "duration": 0
  }
]

(Formatted here; the API answers compact JSON.)

Each entry records the request (method, path, headers, query and parsed body), the response (status, headers and body text), and the duration in milliseconds. outcome says what answered: stub, extension, proxy (also proxied: true) or unmatched. When a stub answered, matchedStubId names it and responseIndex says which of its responses it gave. When that response has callbacks, callbacks lists every call it made:

"callbacks": [
  {"name":"cart","phase":"before","method":"GET","url":"http://127.0.0.1:3302/carts/7","state":"answered","status":200,"durationMs":5,"responseBody":"{\"items\":[{\"sku\":\"tea\",\"price\":4},{\"sku\":\"cake\",\"price\":6}]}"},
  {"name":"notify","phase":"after","method":"POST","url":"http://127.0.0.1:3304/events","state":"pending"}
]

An after call is logged pending and its record settles in place, to answered, failed or skipped, when the call ends. The log keeps the latest 100 requests per imposter, oldest first, and stores up to 10 KB of each response body.

Filters

Query parameter	Default	Description
limit	50	The latest N matching entries
method	none	Only this method (any case)
path	none	Only this exact path
status	none	Only this response status

curl "http://localhost:2525/imposters/2f334551/requests?status=404"

DELETE /imposters/:id/requests clears the log.

Stats

curl http://localhost:2525/imposters/2f334551/stats

{"totalRequests":5,"requestsPerMinute":4918.03,"averageResponseTime":0.4,"errorRate":0.4,"serverErrorRate":0,"requestsByMethod":{"POST":3,"GET":2},"requestsByStatusCode":{"200":1,"201":2,"402":1,"404":1},"lastRequestAt":"2026-10-01T21:17:47.562Z","p50ResponseTime":0,"p95ResponseTime":2,"p99ResponseTime":2,"timeline":[...],"last15Minutes":{"requests":5,"serverErrors":0,"unmatched":1},"stubs":[...],"unmatched":[...],"outbound":[]}

Field	Meaning
totalRequests	Requests received
requestsPerMinute	The rate between the first and the latest request
averageResponseTime, p50ResponseTime, p95ResponseTime, p99ResponseTime	Response times in milliseconds
errorRate	The fraction of responses with a status of 400 or more
serverErrorRate	The fraction with a status of 500 or more
requestsByMethod, requestsByStatusCode	Counts
lastRequestAt	When the latest request arrived
timeline, last15Minutes	The last 15 minutes in 30 buckets of 30 seconds, oldest first, each with its start, requests, serverErrors and unmatched; and their sum
stubs	One row per stub, in matching order: stubId, hits, byResponse, lastHitAt, and nextResponseIndex (absent in random mode)
unmatched	Requests nothing answered, grouped by method and path, most recently seen first; up to 50 groups
outbound	The calls the imposter made, its callbacks and proxy forwards, one edge per target host; see below

Outbound calls

Each edge counts the calls sent to one host:

"outbound": [
  {"host":"127.0.0.1:3303","via":"callback","calls":1,"failed":0,"serverErrors":0,"lastAt":"2026-10-08T09:02:45.659Z","p50":97,"p95":97,"timeline":[...]}
]

via is callback, proxy or both. failed counts calls that got no answer (a timeout, a refused connection), callback answers over 1 MiB, and calls refused because 64 were already in flight; serverErrors counts 5xx answers. p50 and p95 are in milliseconds, over the last 128 calls sent, and timeline has 30 buckets of calls and failed. A call refused at the hop limit was never sent and is not counted. Up to 50 hosts are kept, most recently called first.

DELETE /imposters/:id/stats resets them.

Both are also shown in the imposter’s web UI.