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Serverless Performance Explorer

Lambda REPORT lines → cold-start rate, p50/p95/p99, memory right-sizing and cost per 1M calls.

CloudWatch REPORT lines, JSON log-format platform.report records, or CSV with columns like requestId,duration,billedDuration,memorySize,maxMemoryUsed,initDuration[,function,timestamp]. Separate functions with "=== function: name ===".

USD/GB-s

Default: us-east-1 first tier, verified 2026-10-14.

USD/GB-s
USD

Adds a monthly cost estimate (free tier not deducted).

%

Added to the peak observed memory when suggesting a size.

Try an example: Two functions from CloudWatch REPORT lines · CSV export (arm64, cold starts with billed INIT)

How it works

Paste AWS Lambda REPORT log lines, JSON platform.report records or a CSV/Logs Insights export. Get cold-start rate, init and duration percentiles, memory utilisation with a right-sizing suggestion, and the cost per 1 million invocations on x86_64 and arm64 using the public Lambda prices (overridable).

  • Each REPORT line (plain text or JSON "platform.report") yields Duration, Billed Duration, Memory Size, Max Memory Used and, on cold starts, Init Duration (or SnapStart Restore Duration). "Status: timeout|error" and "Task timed out after" lines mark failed invocations.
  • Cold-start rate = invocations with Init/Restore Duration ÷ all invocations. Percentiles use the nearest-rank method on the observed values.
  • GB-seconds per invocation = Billed Duration (s) × Memory Size (MB) ÷ 1024. If Billed Duration is missing it is estimated as ceil(Duration + Init) because INIT is billed for on-demand functions since 1 Aug 2025.
  • Cost per 1M invocations = price per 1M requests + 1,000,000 × mean GB-s × price per GB-s, for x86_64 and arm64 (first pricing tier, no free tier).
  • Right-sizing: suggested memory = peak Max Memory Used × (1 + headroom), rounded up to 64 MB (128–10,240 MB). Increase if peak use ≥ 90 % of the configured size; decrease if the suggestion is ≤ 75 % of it; otherwise keep. Cost estimates assume the billed duration does not change with memory (CPU scales with memory, so verify).
  • CloudWatch Logs Insights exports report @memorySize/@maxMemoryUsed in bytes; values above 100,000 are converted to MB (10^6 bytes).

Sources

For scripts and AI agents

  • JSON API: POST https://serverlessperformanceexplorer.usefulweb.site/api/v1/calculate (same calculation as this page)
  • Interface description: OpenAPI 3.1 · AI guide: llms.txt
  • MCP server (Streamable HTTP): https://serverlessperformanceexplorer.usefulweb.site/mcp · tool name serverless_performance_explorer
Example request
curl -s -X POST https://serverlessperformanceexplorer.usefulweb.site/api/v1/calculate \
  -H 'content-type: application/json' \
  -d '{…see OpenAPI examples…}'

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