Smoke Test vs Load Test vs Soak Test for APIs

Not every performance run should be a peak-RPS rehearsal. Smoke, load, and soak answer different questions — and should use different duration and quota budgets.

Smoke test

Question: Does the path work under a little traffic?

• Low RPS (often 5–20)
• Short duration (1–3 minutes)
• Ramp-up optional / small
• Watch for 4xx/5xx and obvious timeouts

Use after changing the Postman/curl request, auth headers, or domain — before spending a large duration × RPS hold.

Load test

Question: Can we sustain expected peak with acceptable p95/p99 and errors?

• Target RPS from traffic math
• Minutes-long hold after ramp-up
• Pass/fail criteria written first

This is Loadcurl’s default job: target RPS, ramp-up, duration, then a report. See Load vs Stress vs Performance Testing.

Soak (endurance) test

Question: Does performance drift over time — leaks, saturation, disk, connection exhaustion?

• Moderate RPS (often below peak)
• Long duration (tens of minutes to hours — within plan max duration)
• Watch p99 and error rate over time, not only averages

Soak is still a load profile — same composer — with different intent and patience. Check quota hold first; long × RPS gets expensive.

Stress (for contrast)

Question: Where does it break above peak? Prefer staging. Not the same as soak or smoke.

Quick comparison

Type	RPS	Duration	Primary signal
Smoke	Low	Short	Correctness
Load	Expected peak	Minutes	SLO at peak
Soak	Moderate	Long	Drift / leaks
Stress	Above peak	Until degrade	Breaking point

Suggested Loadcurl sequences

1. Smoke at 10 RPS × 120s
2. Load at target × 600s with 60s ramp-up
3. Optional soak at 50% peak × as long as plan + quota allow
4. Optional stress on staging only

Stop early if the smoke fails — do not burn Growth-plan quota on a bad Authorization header.

Related reading

• What Is Ramp-Up in Load Testing?
• Request Quota Explained
• Pre-Launch Checklist