Scout APM API

Query application performance monitoring data from Scout APM using the REST API.

When to Use

• Investigating slow endpoints or response time regressions
• Listing applications and their metrics (apdex, throughput, error rate, p95)
• Fetching traces for a specific endpoint
• Reviewing error groups and individual error stacktraces
• Checking insights: N+1 queries, memory bloat, slow queries

Do not use for configuring Scout agents or instrumenting code — this is the read-only reporting API.

Setup

API Key

1. Log into Scout APM
2. Go to organization settings
3. Create a named API token
4. Export it in your shell profile:

export SCOUT_API_KEY="your-token-here"

Base URL

https://scoutapm.com/api/v0

Authentication

Every request must include the key via one of:

• Header: X-SCOUT-API: $SCOUT_API_KEY
• Query param: ?key=$SCOUT_API_KEY

All examples below use the header approach.

Quick Reference

# List apps
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" "https://scoutapm.com/api/v0/apps"

# App details
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" "https://scoutapm.com/api/v0/apps/{id}"

# Available metrics for an app
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" "https://scoutapm.com/api/v0/apps/{id}/metrics"

# Metric time-series (requires from/to)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/metrics/{metric_type}?from=2026-02-18T00:00:00Z&to=2026-02-19T00:00:00Z"

# List endpoints (requires from/to)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/endpoints?from=2026-02-18T00:00:00Z&to=2026-02-19T00:00:00Z"

# Endpoint metrics (endpoint is base64-url-encoded)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/endpoints/{endpoint_b64}/metrics/{metric_type}?from=...&to=..."

# List traces for endpoint (max 100, within 7 days)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/endpoints/{endpoint_b64}/traces?from=...&to=..."

# Trace detail (includes spans)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/traces/{trace_id}"

# Error groups (max 100, within 30 days)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/error_groups?from=...&to=..."

# Error group detail (includes latest_error with stacktrace)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/error_groups/{error_id}"

# Individual errors in a group (max 100)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/error_groups/{error_id}/errors"

# All insights (cached 5 min)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/insights"

# Insights by type: n_plus_one | memory_bloat | slow_query
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/insights/{type}?limit=20"

# Insights history (cursor-paginated)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/insights/history?from=...&to=...&limit=10"

# Insights history by type
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/insights/history/{type}?from=...&to=...&limit=10"

Endpoints Reference

Applications

Metrics

Metric types: apdex, response_time, response_time_95th, errors, throughput, queue_time

Endpoints

Endpoint encoding: The {endpoint} path segment must be Base64 URL-encoded.

# Encode "UsersController#index" → base64
echo -n "UsersController#index" | base64
# VXNlcnNDb250cm9sbGVyI2luZGV4

Traces

Trace detail includes: id, time, total_call_time, mem_delta, metric_name, uri, context, git_sha, allocations_count, limited, spans[]. V2 traces also include transaction_id and hostname.

Errors

Each error includes: message, created_at, request_params, request_uri, location, request_session, trace (stacktrace lines), context.

Insights

Insight types: n_plus_one, memory_bloat, slow_query

Pagination: Cursor-based. Response includes pagination.has_more, pagination.pagination_cursor, and pagination.next_pagination_page. Pass pagination_direction=forward (default) or backward.

Time Steps

Duration determines the resolution of returned time-series data:

Response Format

All responses follow a standard envelope:

{
  "header": {
    "status": { "code": 200, "message": "OK" },
    "apiVersion": "0.1"
  },
  "results": { ... }
}

Error responses use the same envelope with codes 403 (bad key), 404 (not found), or 422 (bad params).

Workflow: Investigate a Slow Endpoint

# 1. Find the app
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" "https://scoutapm.com/api/v0/apps" | jq '.results.apps[] | {id, name}'

# 2. List endpoints sorted by response time (last 24h)
FROM=$(date -u -v-1d +%Y-%m-%dT%H:%M:%SZ)  # macOS
TO=$(date -u +%Y-%m-%dT%H:%M:%SZ)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/endpoints?from=$FROM&to=$TO" \
  | jq '.results | sort_by(-.response_time) | .[:10] | .[] | {name, response_time, throughput, error_rate}'

# 3. Get p95 response time series for the slowest endpoint
ENDPOINT_B64=$(echo -n "Controller#action" | base64)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/endpoints/$ENDPOINT_B64/metrics/response_time_95th?from=$FROM&to=$TO"

# 4. Pull traces to find the slow requests
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/endpoints/$ENDPOINT_B64/traces?from=$FROM&to=$TO" \
  | jq '.results.traces | sort_by(-.total_call_time) | .[:5]'

# 5. Inspect the slowest trace's spans
TRACE_ID=12345
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/traces/$TRACE_ID" \
  | jq '.results.trace.spans'

Workflow: Review Errors

# 1. List error groups (last 7 days)
FROM=$(date -u -v-7d +%Y-%m-%dT%H:%M:%SZ)
TO=$(date -u +%Y-%m-%dT%H:%M:%SZ)
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/error_groups?from=$FROM&to=$TO" \
  | jq '.results.error_groups | sort_by(-.errors_count) | .[:10] | .[] | {id, name, message, errors_count, last_error_at}'

# 2. Get detail + latest stacktrace
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/error_groups/{error_id}" \
  | jq '.results.error_group | {name, message, status, errors_count, latest_error}'

Workflow: Check Insights

# Quick overview — are there N+1s, memory bloat, or slow queries?
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/insights" \
  | jq '.results.insights | to_entries[] | {type: .key, count: .value.count, new: .value.new_count}'

# Drill into N+1 queries
curl -sS -H "X-SCOUT-API: $SCOUT_API_KEY" \
  "https://scoutapm.com/api/v0/apps/{id}/insights/n_plus_one?limit=10"

Common Pitfalls

• Missing from/to params — most endpoints require ISO 8601 timestamps; omitting them returns 422
• Endpoint encoding — the {endpoint} path segment must be base64-encoded; raw strings like Users#index will 404
• Trace time window — traces endpoint is limited to a 7-day window
• Error group time window — error_groups endpoint is limited to 30 days
• Insights cache — current insights are cached for 5 minutes; don’t poll more frequently
• Max results — traces and error lists cap at 100 items; no built-in pagination for those endpoints
• Time step granularity — you don’t control it; it’s determined by the duration of your from/to window (see Time Steps table)