BLASTA

REST API load testing template

Collection, single resource and a write.

Category APIStack AnyJobs 19

About this REST API load test

A starting point for any JSON REST API: reading a collection, fetching a single resource, a HEAD probe and a POST that creates data. It shows the latency and error rate of the common read and write paths, and the enterprise plan then pushes the API through smoke, load, stress, spike and soak stages.

It holds 19 ready-made jobs: 4 single scenarios and an enterprise test plan of 15 stages to run in order, 13 of them with pass/fail targets (SLOs). Each job is a plain request pattern you can change before running.

Scenarios include REST collection, REST single item, REST HEAD probe and REST POST create.

How to load test REST API

  1. Open the template in BLASTA.
  2. Set url to point at your own REST API system, ideally a staging copy.
  3. Pick a job and choose the rate and duration.
  4. Start the run and watch requests per second, latency percentiles and errors live; the result is saved to your history.

What you set before running

url
Site base URL, no trailing slash
collection
Collection path segment, e.g. items
id
ID of an existing resource

Test scenarios (4)

REST HEAD probe

Read-only

Cheap reachability check that returns headers only.

REST POST create

Writes data

WRITES. Needs an API token in the headers and will create real records. Staging only.

Enterprise test plan (15)

Run in order: smoke, baseline, load, stress, spike, soak, breakpoint and failover window, each with pass/fail targets.

REST API (generic): 01 smoke

Read-only

Enterprise plan, step 1 of 10. One request a second for 30 seconds. Run this first, every time: it proves the address, credentials and headers are right and that the environment is up before any real load is applied. Gate: zero errors. Reference request: REST collection.

REST API (generic): 02 baseline (20% load)

Read-only

Step 2 of 10. About a fifth of normal traffic for 5 minutes: the uncontended latency of this request. Every later result is judged against it, so record p50 and p95. Gate: at most 0.5% errors and the default latency targets. Reference request: REST collection.

REST API (generic): 03 average load (SLO check)

Read-only

Step 3 of 10. Normal busy-hour traffic for 10 minutes. The rate is the reference job's rate: raise it to your measured production peak-hour rate. This is the run that proves (or breaks) your SLO. Gate: at most 1% errors, p95 and p99 inside the targets. Reference request: REST collection.

REST API (generic): 04 peak load (2x average)

Read-only

Step 4 of 10. Twice the average for 10 minutes: the busiest hour of the year plus headroom. Latency may rise, but must stay in SLO; if it does not, you have no headroom. Gate: at most 2% errors, latency targets doubled. Reference request: REST collection.

REST API (generic): 05 stress (ramp to 4x)

Read-only

Step 5 of 10. Ramps to four times average over 10 minutes, then holds for 2. Finds where it degrades and HOW: gracefully (latency rises, errors stay low) or badly (errors, timeouts, crashes, restarts). Observation only, no gate. Reference request: REST collection.

REST API (generic): 06 spike (10x in 10 s)

Read-only

Step 6 of 10. Reaches ten times average within 10 seconds and holds for 2 minutes: a campaign email, a news link, a failover. Checks autoscaling, queue limits and load shedding. Gate: at most 5% errors, because shedding load is acceptable and crashing is not. Reference request: REST collection.

REST API (generic): 07 recovery after the spike

Read-only

Step 7 of 10. Run IMMEDIATELY after the spike, at average load for 5 minutes. Latency and errors must return to the baseline from step 2. If they do not, something is stuck: queues, connection pools, GC, an autoscaler cool-down. Gate: same as average load. Reference request: REST collection.

REST API (generic): 08 soak (1 hour at 60%)

Read-only

Step 8 of 10. One hour of steady load. Finds leaks and slow decay in memory, connections, file descriptors, disk, log volume and cache churn. Watch the resource graphs: any line that climbs and never flattens is a finding. Gate: at most 0.5% errors. Reference request: REST collection.

REST API (generic): 09 breakpoint (find the ceiling)

Read-only

Step 9 of 10. Ramps to twenty times average over 20 minutes. Stop it when errors pass about 5%: the rate at that moment is your ceiling, and ceiling divided by peak is your capacity margin. Use a production-like environment, never production. Reference request: REST collection.

REST API (generic): 10 resilience window (failover / deploy)

Read-only

Step 10 of 10. Average load for 15 minutes. About 5 minutes in, cause the event you are testing: kill a pod or node, fail over the database, roll out a new version, drain a zone. Errors in the window are your real availability loss. Gate: at most 1% errors overall; read the time series for how long the dip lasted. Reference request: REST collection.

REST API (generic): no keep-alive (new connection per request)

Read-only

Sends Connection: close, so every request pays for a new TCP and TLS handshake: the cost for clients that do not reuse connections (scripts, some mobile SDKs, health checkers). Shows load balancer and TLS termination limits. Reference request: REST collection.

REST API (generic): large cookies (~4 KB header)

Read-only

Adds a 4 KB Cookie header, like a logged-in user with many tracking cookies. Proxies and servers reject headers around 8 KB, so this shows how close you are to that limit. Reference request: REST collection.

Frequently asked questions

What does the REST API load test cover?

The REST API template has 19 jobs: 4 single scenarios and an enterprise test plan of 15 stages (smoke, baseline, load, stress, spike, soak, breakpoint and failover window). Scenarios include REST collection, REST single item, REST HEAD probe and REST POST create. 13 of them have pass/fail targets (SLOs), so a run can be judged against limits you set.

How do I load test REST API with BLASTA?

Open the template in BLASTA and set url, then pick a job and start it. Results stream live: requests per second, latency percentiles and errors, and the run is kept in your history. To run from the command line, use blasta preset new api-rest with your address.

Is it safe to run the REST API load test against production?

Of the 19 jobs, 18 are read-only, 1 write data and 0 change state. Run the writing and state-changing jobs against a staging system, never against production data. Only test systems you own or have permission to test.

Related templates

Run a load test

Point BLASTA at something you own, choose how hard to hit it, and press Start test. Results stream in live.

1 What do you want to test? Use a template

Request headers

2 How hard should it hit?

Advanced limits
Pass / fail targets (SLO) optional
The result is marked SLO met or SLO missed. The same targets live in a job file, where blasta run exits 2 on a miss so CI or Kubernetes can gate a release.

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