Mock Distributed Trace and Span API

MOCK DATA

Generate coherent mock distributed traces and individual spans with bounded timing, parentage, service filters and reproducible failures.

Generated test data for fixtures and development

Base URL: /api/traces
Category: Developer Tools
Capabilities: 2 routes Seedable
Last updated: July 29, 2026

GET /api/traces Generate complete mock traces with coherent span trees Returns a list

Live requestRuns against the public API

No key required

GET/api/traces?service=checkout&spanCount=6&count=10&seed=42

Request parameters

service

Constrain the trace's root service. Omit for a mix.

status

Constrain trace status. Error guarantees at least one failed span.

minDurationMsdefault 20

Inclusive minimum total trace duration in milliseconds.

maxDurationMsdefault 2000

Inclusive maximum total trace duration; must be at least minDurationMs.

spanCountdefault 4

Exact number of spans nested in every generated trace.

windowMinutesdefault 60

Trace start is sampled within this many minutes at or before resolved asOf.

asOf

Window end. Defaults to the current UTC day's final millisecond and is echoed for replay.

Advanced response options7 options

countdefault 10

How many records to generate (1–100).

seed

Deterministic output: the same seed always returns the same records. Omit for random (the used seed is echoed in meta.seed).

fields

Return only these fields (comma-separated). Mutually exclusive with 'exclude'.

exclude

Return all fields except these (comma-separated).

formatdefault json

Response format: json envelope, ndjson (one record per line) or csv.

prettydefault false

Pretty-print the JSON response.

unwrapdefault false

Drop the envelope: return the raw array/object without data/meta wrapper.

Response

Example parameters are ready. Send the request to inspect the live response.

Route reference

Code, request parameters, response fields and verified examples 14 params · 9 fields · 2 examples

Code samples Ready-to-copy requests in 4 languages

curl JavaScript Python PHP

curl "https://randomapi.dev/api/traces?service=checkout&spanCount=6&seed=42&count=10"

const res = await fetch("https://randomapi.dev/api/traces?service=checkout&spanCount=6&seed=42&count=10");
const { data, meta } = await res.json();

import requests

data = requests.get("https://randomapi.dev/api/traces?service=checkout&spanCount=6&seed=42&count=10").json()["data"]

$json = json_decode(file_get_contents(
  "https://randomapi.dev/api/traces?service=checkout&spanCount=6&seed=42&count=10"
), true);
$data = $json["data"];

Parameters Route-specific request inputs 7

Parameter	Type	Default & allowed	Description
`service`	enum	allowed: gateway \| checkout \| catalog \| payments \| worker example: checkout	Constrain the trace's root service. Omit for a mix.
`status`	enum	allowed: ok \| error example: error	Constrain trace status. Error guarantees at least one failed span.
`minDurationMs`	int	default: 20 allowed: 1 – 60000 example: 100	Inclusive minimum total trace duration in milliseconds.
`maxDurationMs`	int	default: 2000 allowed: 1 – 60000 example: 5000	Inclusive maximum total trace duration; must be at least minDurationMs.
`spanCount`	int	default: 4 allowed: 1 – 8 example: 6	Exact number of spans nested in every generated trace.
`windowMinutes`	int	default: 60 allowed: 1 – 1440 example: 120	Trace start is sampled within this many minutes at or before resolved asOf.
`asOf`	date	example: 2026-07-10T23:59:59.999Z	Window end. Defaults to the current UTC day's final millisecond and is echoed for replay.

service enum

Constrain the trace's root service. Omit for a mix.

allowed: gateway | checkout | catalog | payments | worker

example: service=checkout

status enum

Constrain trace status. Error guarantees at least one failed span.

allowed: ok | error

example: status=error

minDurationMs int

Inclusive minimum total trace duration in milliseconds.

default: 20

allowed: 1 – 60000

example: minDurationMs=100

maxDurationMs int

Inclusive maximum total trace duration; must be at least minDurationMs.

default: 2000

allowed: 1 – 60000

example: maxDurationMs=5000

spanCount int

Exact number of spans nested in every generated trace.

default: 4

allowed: 1 – 8

example: spanCount=6

windowMinutes int

Trace start is sampled within this many minutes at or before resolved asOf.

default: 60

allowed: 1 – 1440

example: windowMinutes=120

asOf date

Window end. Defaults to the current UTC day's final millisecond and is echoed for replay.

example: asOf=2026-07-10T23:59:59.999Z

Universal parameters Shared response and formatting options 7

Parameter	Type	Default & allowed	Description
`count`	int	default: 10 allowed: 1 – 100 example: 3	How many records to generate (1–100).
`seed`	int	example: 42	Deterministic output: the same seed always returns the same records. Omit for random (the used seed is echoed in meta.seed).
`fields`	list	example: traceId,name	Return only these fields (comma-separated). Mutually exclusive with 'exclude'.
`exclude`	list	example: spans	Return all fields except these (comma-separated).
`format`	enum	default: json allowed: json \| ndjson \| csv example: csv	Response format: json envelope, ndjson (one record per line) or csv.
`pretty`	boolean	default: false example: true	Pretty-print the JSON response.
`unwrap`	boolean	default: false example: true	Drop the envelope: return the raw array/object without data/meta wrapper.

count int

How many records to generate (1–100).

default: 10

allowed: 1 – 100

example: count=3

seed int

Deterministic output: the same seed always returns the same records. Omit for random (the used seed is echoed in meta.seed).

example: seed=42

fields list

Return only these fields (comma-separated). Mutually exclusive with 'exclude'.

example: fields=traceId,name

exclude list

Return all fields except these (comma-separated).

example: exclude=spans

format enum

Response format: json envelope, ndjson (one record per line) or csv.

default: json

allowed: json | ndjson | csv

example: format=csv

pretty boolean

Pretty-print the JSON response.

default: false

example: pretty=true

unwrap boolean

Drop the envelope: return the raw array/object without data/meta wrapper.

default: false

example: unwrap=true

Response schema Fields returned in each record 9

Field	Type	Description	Example
`traceId`	string	Unique fictional 32-hex trace identifier.	0000000076cc47a8b2caa2cf7131537a
`name`	string	Root operation name coherent with service.	create checkout
`service`	string	Root service selected by the service filter or generator.	checkout
`startTime`	string (ISO 8601)	Trace start inside the requested window at or before resolved asOf.	2026-07-10T23:14:22.031Z
`durationMs`	integer	Total duration inside the requested inclusive bounds.	842
`status`	string	ok or error, derived coherently from nested span status.	error
`rootSpanId`	string	Identifier of spans[0], whose parent is null.	0000000066f327f2
`spanCount`	integer	Exact number of objects in spans.	4
`spans`	object[]	Bounded parent-first span tree with offsets, durations, status and nullable error codes.	[{"spanId":"0000000066f327f2","parentSpanId":null,"name":"create checkout","service":"checkout","kind":"server","startOffsetMs":0,"durationMs":842,"status":"ok","errorCode":null}]

traceId string

Unique fictional 32-hex trace identifier.

example: 0000000076cc47a8b2caa2cf7131537a

name string

Root operation name coherent with service.

example: create checkout

service string

Root service selected by the service filter or generator.

example: checkout

startTime string (ISO 8601)

Trace start inside the requested window at or before resolved asOf.

example: 2026-07-10T23:14:22.031Z

durationMs integer

Total duration inside the requested inclusive bounds.

example: 842

status string

ok or error, derived coherently from nested span status.

example: error

rootSpanId string

Identifier of spans[0], whose parent is null.

example: 0000000066f327f2

spanCount integer

Exact number of objects in spans.

example: 4

spans object[]

Bounded parent-first span tree with offsets, durations, status and nullable error codes.

example: [{"spanId":"0000000066f327f2","parentSpanId":null,"name":"create checkout","service":"checkout","kind":"server","startOffsetMs":0,"durationMs":842,"status":"ok","errorCode":null}]

Documented examples

Build-generated requests and complete responses 2

Checkout traces with six spans /api/traces?service=checkout&spanCount=6&seed=42&count=10

GET /api/traces?service=checkout&spanCount=6&seed=42&count=10

{
  "data": [
    {
      "traceId": "0000000029ff11dec8095cf565312cf8",
      "name": "reserve order",
      "service": "checkout",
      "startTime": "2026-07-29T23:00:15.697Z",
      "durationMs": 1361,
      "status": "ok",
      "rootSpanId": "00000000958016cf",
      "spanCount": 6,
      "spans": [
        {
          "spanId": "00000000958016cf",
          "parentSpanId": null,
          "name": "reserve order",
          "service": "checkout",
          "kind": "server",
          "startOffsetMs": 0,
          "durationMs": 1361,
          "status": "ok",
          "errorCode": null
        },
        {
          "spanId": "00000001b6a5c85e",
          "parentSpanId": "00000000958016cf",
          "name": "validate basket",
          "service": "checkout",
          "kind": "producer",
          "startOffsetMs": 494,
          "durationMs": 377,
          "status": "ok",
          "errorCode": null
        },
        {
          "spanId": "00000002ac58cdd4",
          "parentSpanId": "00000000958016cf",
          "name": "create checkout",
          "service": "checkout",
          "kind": "server",
    …
    "generatedAt": "2026-07-29T08:13:22.000Z"
  }
}

Slow failed traces /api/traces?status=error&minDurationMs=2000&maxDurationMs=5000&windowMinutes=120&count=20

GET /api/traces?status=error&minDurationMs=2000&maxDurationMs=5000&windowMinutes=120&count=20

{
  "data": [
    {
      "traceId": "000000006b87c24316010d14615edf36",
      "name": "list products",
      "service": "catalog",
      "startTime": "2026-07-29T22:21:26.745Z",
      "durationMs": 4032,
      "status": "error",
      "rootSpanId": "00000000958016cf",
      "spanCount": 4,
      "spans": [
        {
          "spanId": "00000000958016cf",
          "parentSpanId": null,
          "name": "list products",
          "service": "catalog",
          "kind": "server",
          "startOffsetMs": 0,
          "durationMs": 4032,
          "status": "ok",
          "errorCode": null
        },
        {
          "spanId": "00000001b6a5c85e",
          "parentSpanId": "00000000958016cf",
          "name": "search catalog",
          "service": "catalog",
          "kind": "internal",
          "startOffsetMs": 3425,
          "durationMs": 50,
          "status": "ok",
          "errorCode": null
        },
        {
          "spanId": "00000002ac58cdd4",
          "parentSpanId": "00000000958016cf",
          "name": "load product",
          "service": "catalog",
          "kind": "client",
    …
    "generatedAt": "2026-07-29T08:13:22.000Z"
  }
}

GET /api/traces/spans Generate individual filtered mock spans Returns a list

Live requestRuns against the public API

No key required

GET/api/traces/spans?service=payments&kind=client&count=20&seed=42

Request parameters

service

Constrain every span to this service. Omit for a mix.

kind

Constrain every span to this span kind. Omit for a mix.

status

Constrain every span to ok or error.

minDurationMsdefault 5

Inclusive minimum span duration in milliseconds.

maxDurationMsdefault 1000

Inclusive maximum span duration; must be at least minDurationMs.

windowMinutesdefault 60

Span start is sampled within this many minutes at or before resolved asOf.

asOf

Window end. Defaults to the current UTC day's final millisecond and is echoed for replay.

Advanced response options7 options

countdefault 10

How many records to generate (1–100).

seed

Deterministic output: the same seed always returns the same records. Omit for random (the used seed is echoed in meta.seed).

fields

Return only these fields (comma-separated). Mutually exclusive with 'exclude'.

exclude

Return all fields except these (comma-separated).

formatdefault json

Response format: json envelope, ndjson (one record per line) or csv.

prettydefault false

Pretty-print the JSON response.

unwrapdefault false

Drop the envelope: return the raw array/object without data/meta wrapper.

Response

Example parameters are ready. Send the request to inspect the live response.

Route reference

Code, request parameters, response fields and verified examples 14 params · 11 fields · 2 examples

Code samples Ready-to-copy requests in 4 languages

curl JavaScript Python PHP

curl "https://randomapi.dev/api/traces/spans?service=payments&kind=client&seed=42&count=20"

const res = await fetch("https://randomapi.dev/api/traces/spans?service=payments&kind=client&seed=42&count=20");
const { data, meta } = await res.json();

import requests

data = requests.get("https://randomapi.dev/api/traces/spans?service=payments&kind=client&seed=42&count=20").json()["data"]

$json = json_decode(file_get_contents(
  "https://randomapi.dev/api/traces/spans?service=payments&kind=client&seed=42&count=20"
), true);
$data = $json["data"];

Parameters Route-specific request inputs 7

Parameter	Type	Default & allowed	Description
`service`	enum	allowed: gateway \| checkout \| catalog \| payments \| worker example: payments	Constrain every span to this service. Omit for a mix.
`kind`	enum	allowed: server \| client \| producer \| consumer \| internal example: client	Constrain every span to this span kind. Omit for a mix.
`status`	enum	allowed: ok \| error example: ok	Constrain every span to ok or error.
`minDurationMs`	int	default: 5 allowed: 1 – 60000 example: 20	Inclusive minimum span duration in milliseconds.
`maxDurationMs`	int	default: 1000 allowed: 1 – 60000 example: 2000	Inclusive maximum span duration; must be at least minDurationMs.
`windowMinutes`	int	default: 60 allowed: 1 – 1440 example: 240	Span start is sampled within this many minutes at or before resolved asOf.
`asOf`	date	example: 2026-07-10T23:59:59.999Z	Window end. Defaults to the current UTC day's final millisecond and is echoed for replay.

service enum

Constrain every span to this service. Omit for a mix.

allowed: gateway | checkout | catalog | payments | worker

example: service=payments

kind enum

Constrain every span to this span kind. Omit for a mix.

allowed: server | client | producer | consumer | internal

example: kind=client

status enum

Constrain every span to ok or error.

allowed: ok | error

example: status=ok

minDurationMs int

Inclusive minimum span duration in milliseconds.

default: 5

allowed: 1 – 60000

example: minDurationMs=20

maxDurationMs int

Inclusive maximum span duration; must be at least minDurationMs.

default: 1000

allowed: 1 – 60000

example: maxDurationMs=2000

windowMinutes int

Span start is sampled within this many minutes at or before resolved asOf.

default: 60

allowed: 1 – 1440

example: windowMinutes=240

asOf date

Window end. Defaults to the current UTC day's final millisecond and is echoed for replay.

example: asOf=2026-07-10T23:59:59.999Z

Universal parameters Shared response and formatting options 7

Parameter	Type	Default & allowed	Description
`count`	int	default: 10 allowed: 1 – 100 example: 3	How many records to generate (1–100).
`seed`	int	example: 42	Deterministic output: the same seed always returns the same records. Omit for random (the used seed is echoed in meta.seed).
`fields`	list	example: traceId,spanId	Return only these fields (comma-separated). Mutually exclusive with 'exclude'.
`exclude`	list	example: attributes	Return all fields except these (comma-separated).
`format`	enum	default: json allowed: json \| ndjson \| csv example: csv	Response format: json envelope, ndjson (one record per line) or csv.
`pretty`	boolean	default: false example: true	Pretty-print the JSON response.
`unwrap`	boolean	default: false example: true	Drop the envelope: return the raw array/object without data/meta wrapper.

count int

How many records to generate (1–100).

default: 10

allowed: 1 – 100

example: count=3

seed int

Deterministic output: the same seed always returns the same records. Omit for random (the used seed is echoed in meta.seed).

example: seed=42

fields list

Return only these fields (comma-separated). Mutually exclusive with 'exclude'.

example: fields=traceId,spanId

exclude list

Return all fields except these (comma-separated).

example: exclude=attributes

format enum

Response format: json envelope, ndjson (one record per line) or csv.

default: json

allowed: json | ndjson | csv

example: format=csv

pretty boolean

Pretty-print the JSON response.

default: false

example: pretty=true

unwrap boolean

Drop the envelope: return the raw array/object without data/meta wrapper.

default: false

example: unwrap=true

Response schema Fields returned in each record 11

Field	Type	Description	Example
`traceId`	string	Unique fictional trace id for this standalone span fixture.	0000000076cc47a8b2caa2cf7131537a
`spanId`	string	Unique fictional 16-hex span id.	0000000066f327f2
`parentSpanId` nullable	string	Null for generated server roots; otherwise a fictional parent id.	00000000a2cf7131
`name`	string	Operation coherent with service.	authorize payment
`service`	string	Generated or requested service.	payments
`kind`	string	server, client, producer, consumer or internal.	client
`startTime`	string (ISO 8601)	Span start inside the requested sampling window.	2026-07-10T23:42:10.002Z
`durationMs`	integer	Span duration inside requested bounds.	127
`status`	string	ok or error.	ok
`errorCode` nullable	string	Service-specific code for error spans; otherwise null.	null
`attributes`	object	Small safe example attributes coherent with kind.	{"method":"POST","path":"/api/checkout","statusCode":201}

traceId string

Unique fictional trace id for this standalone span fixture.

example: 0000000076cc47a8b2caa2cf7131537a

spanId string

Unique fictional 16-hex span id.

example: 0000000066f327f2

parentSpanId string nullable

Null for generated server roots; otherwise a fictional parent id.

example: 00000000a2cf7131

name string

Operation coherent with service.

example: authorize payment

service string

Generated or requested service.

example: payments

kind string

server, client, producer, consumer or internal.

example: client

startTime string (ISO 8601)

Span start inside the requested sampling window.

example: 2026-07-10T23:42:10.002Z

durationMs integer

Span duration inside requested bounds.

example: 127

status string

ok or error.

example: ok

errorCode string nullable

Service-specific code for error spans; otherwise null.

example: null

attributes object

Small safe example attributes coherent with kind.

example: {"method":"POST","path":"/api/checkout","statusCode":201}

Documented examples

Build-generated requests and complete responses 2

Payment client spans /api/traces/spans?service=payments&kind=client&seed=42&count=20

GET /api/traces/spans?service=payments&kind=client&seed=42&count=20

{
  "data": [
    {
      "traceId": "00000000a958016cfb6a5c85eac58cdd",
      "spanId": "0000000040fb1586",
      "parentSpanId": "000000013c1d1cff",
      "name": "capture payment",
      "service": "payments",
      "kind": "client",
      "startTime": "2026-07-29T23:29:42.718Z",
      "durationMs": 187,
      "status": "ok",
      "errorCode": null,
      "attributes": {
        "method": "POST",
        "path": "/api/items",
        "statusCode": 200
      }
    },
    {
      "traceId": "00000001078f248abeccba6fd45df91c",
      "spanId": "0001000036673e8f",
      "parentSpanId": "00010001cae90de6",
      "name": "authorize payment",
      "service": "payments",
      "kind": "client",
      "startTime": "2026-07-29T23:21:41.589Z",
      "durationMs": 351,
      "status": "ok",
      "errorCode": null,
      "attributes": {
        "method": "POST",
        "path": "/api/orders",
        "statusCode": 201
      }
    },
    {
      "traceId": "0000000215790902c05ac838fecf0b9c",
      "spanId": "000200004166f967",
      "parentSpanId": "000200010555a0ee",
    …
    "generatedAt": "2026-07-29T08:13:22.000Z"
  }
}

Failed queue consumers /api/traces/spans?service=worker&kind=consumer&status=error&minDurationMs=50&maxDurationMs=500&count=15

GET /api/traces/spans?service=worker&kind=consumer&status=error&minDurationMs=50&maxDurationMs=500&count=15

{
  "data": [
    {
      "traceId": "000000007a958016cfb6a5c85eac58cd",
      "spanId": "00000000d40fb158",
      "parentSpanId": "0000000163c1d1cf",
      "name": "retry task",
      "service": "worker",
      "kind": "consumer",
      "startTime": "2026-07-29T23:30:14.480Z",
      "durationMs": 273,
      "status": "error",
      "errorCode": "JOB_FAILED",
      "attributes": {
        "messagingSystem": "demo-broker",
        "destination": "events"
      }
    },
    {
      "traceId": "000000010078f248abeccba6fd45df91",
      "spanId": "00010000c36673e8",
      "parentSpanId": "00010001fcae90de",
      "name": "publish result",
      "service": "worker",
      "kind": "consumer",
      "startTime": "2026-07-29T23:19:40.439Z",
      "durationMs": 213,
      "status": "error",
      "errorCode": "JOB_FAILED",
      "attributes": {
        "messagingSystem": "demo-broker",
        "destination": "events"
      }
    },
    {
      "traceId": "00000002d15790902c05ac838fecf0b9",
      "spanId": "00020000c4166f96",
      "parentSpanId": "0002000170555a0e",
      "name": "retry task",
      "service": "worker",
    …
    "generatedAt": "2026-07-29T08:13:22.000Z"
  }
}

About this API

Coverage, behavior and common use cases

Coverage & behavior

Generates compact, fictional distributed tracing fixtures for waterfall views, latency tables and observability demos. The root route returns one complete trace per record with a bounded span tree. Every child starts inside the trace, finishes no later than the trace, and references an earlier span as its parent. An error trace always contains at least one error span; an ok trace contains none.

service, status, duration bounds and spanCount genuinely constrain complete traces. /spans emits individual span records and adds kind filtering for server, client, producer, consumer and internal work. Timestamps are sampled from a window ending at resolved asOf; it defaults to the current UTC day's end and is echoed so a seeded response can be replayed later.

These records are intentionally generic mock data. Their identifiers have familiar trace/span lengths, but the endpoint does not claim OpenTelemetry, Zipkin, Jaeger or W3C propagation conformance. Attributes use safe example paths and a fictional broker; no request headers, credentials, customer data or real hosts are generated.

Use it for

Populate a trace waterfall with coherent parent-child spans and durations
Test error-only observability filters with reproducible failed spans
Generate safe span-table fixtures without exporting production telemetry

Frequently asked questions

Practical answers about this endpoint 4

Are child spans contained inside their trace duration?

Yes. Every child has a non-negative start offset and a duration that ends at or before the trace duration.

Does an error trace always include an error span?

Yes. Error traces contain at least one failed span with an error code; ok traces contain no failed spans.

Are these OpenTelemetry spans?

No. They are compact generic mock fixtures and make no telemetry-vendor or protocol-conformance claim.

Can the endpoint emit real request data?

No. Operations, paths, services, identifiers and attributes are generated fixtures with no headers, secrets or real hosts.

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GET /api/traces Generate complete mock traces with coherent span trees Returns a list

Request parameters

Response

Route reference

Documented examples

GET /api/traces/spans Generate individual filtered mock spans Returns a list

Request parameters

Response

Route reference

Documented examples

About this API

Coverage & behavior

Use it for

Frequently asked questions

Related APIs