Free load testing service for APIs and websites.
Run distributed HTTP load tests from your browser or CI/CD in seconds. Start free, watch live results, set p95 and error-rate thresholds, compare runs, and validate APIs or websites without provisioning workers or maintaining a Grafana stack.
Start free load testing in minutes.
Create a test scenario, hit run, and watch live data immediately. Whether you start from the dashboard or CI/CD, LoadTester keeps free load testing simple for APIs, websites, and critical user flows.
Real test data, not a wall of logs.
Launch a free load test, watch the important numbers while it runs, then review a clean result your team can act on.
A free load testing service with the workflow teams need.
LoadTester is a modern load testing service for HTTP load testing, API load testing, and website performance checks. Start for free, then keep the workflows developers care about: live analytics, thresholds, CI/CD automation, and repeatable reports.
Instant distributed execution, no worker fleet required.
Start distributed load tests in seconds with a managed service instead of building worker fleets yourself. Your team focuses on results — LoadTester handles worker scaling, coordination, and execution flow.
Live analytics
Watch requests, latency, failures, throughput, and bottlenecks in real time while your test is running.
Smart auto-stop
Set failure or latency thresholds and automatically stop tests when things go sideways.
CI/CD ready · Webhooks · Slack & email alerts.
Run tests on every deploy, every PR, or every release candidate. Trigger alerts, workflows, and follow-up actions from your test results with simple webhook integrations.
Start with the exact performance question you need to answer.
Choose by test type, architecture, traffic pattern, or delivery workflow. Each page targets a distinct performance decision and links to a deeper implementation guide where one exists.
Core test types
REST and HTTP scenarios, RPS/VUs and thresholds.
Website load testingTraffic, latency, errors and web-system capacity.
Distributed load testingScale traffic without maintaining worker fleets.
Stress testingFind saturation, failure behavior and recovery.
Spike testingRehearse sudden traffic surges and scaling lag.
Soak testingFind slow degradation and resource exhaustion.
Capacity & scale
Measure sustainable traffic and operating headroom.
Scalability testingMeasure capacity gained by additional resources.
Concurrent user testingModel session overlap, pacing and generated RPS.
High-traffic websitesPrepare launches, campaigns and event peaks.
Kubernetes load testingValidate HPA, pod readiness and scaling lag.
Serverless load testingTest cold starts, concurrency and throttling.
APIs & architecture
Methods, JSON, authentication and endpoint mix.
Microservices load testingExpose dependency and fan-out bottlenecks.
Backend load testingDrive server-side HTTP capacity directly.
Rate-limit testingValidate 429s, burst limits and recovery windows.
Mobile API load testingModel resume bursts, sync, retries and version skew.
Authentication load testingTest login waves, token issuance and identity limits.
Business & delivery workflows
Test tenant mix, shared resources and noisy neighbors.
Ecommerce performancePrepare browse-to-checkout traffic for sales peaks.
Checkout load testingValidate transactional capacity and dependencies.
CI/CD load testingUse performance thresholds as delivery gates.
DevOps load testingLayer fast gates, scheduled tests and release checks.
Pre-release performanceCompare release candidates with a known baseline.
Performance regressionTrack release-to-release latency and capacity drift.
Free load testing calculators & guides
Plan the test before you run it: turn traffic into concurrent users and RPS, size virtual users, compute p95/p99 from raw timings, and fix the errors that show up under load.
Turn monthly or daily sessions, session length and peak-hour share into average and peak concurrent users,…
Requests per Second (RPS) CalculatorCalculate average, peak and target requests per second from daily requests or users, a peak factor and…
Latency Percentile Calculator (p50, p95, p99)Paste response times in ms and get p50, p90, p95, p99, p99.9, mean and a histogram. Shows nearest-rank and…
Think Time and Pacing CalculatorCalculate how many virtual users you need, the pacing interval per iteration and the max throughput from…
Error Budget and SLO CalculatorEnter an SLO such as 99.9% and a window to get allowed downtime, allowed failed requests and burn-rate times,…
Apdex CalculatorCalculate Apdex from satisfied, tolerating and frustrated counts or raw latencies with threshold T. See the…
Bandwidth Calculator for Load Tests and APIsConvert requests per second and response size into Mbps or Gbps, GB per load test, hour and month, and egress…
Database Connection Pool Size CalculatorSize a database connection pool per instance from RPS, queries per request and query time, check the total…
Server Capacity CalculatorWork out how many servers or pods you need from peak RPS, per-instance RPS measured in a load test and target…
Retry Amplification CalculatorCalculate how retries at each layer multiply load on a failing dependency: worst case, expected load at a…
502 Bad Gateway Under Load: How to Find the CauseWhy nginx, ALB or Cloudflare return 502 during a load test: crashes, OOM kills, keep-alive timeout…
Little's Law in Load TestingLittle's Law (L = λW) applied to load tests: VUs = RPS × (response time + think time), worked examples, and…
Black Friday 2026 Load Testing Checklist: A 30-Day CountdownA dated 30-day Black Friday 2026 load testing plan: forecast peak RPS from last year, find the ceiling, fix,…
Start load testing free, then scale when needed.
Use the free plan for quick API and website checks. Starter covers most sites and APIs (up to 250 concurrent users); pick Pro for production launches, Slack alerts and regression tracking.
Prices in USD per month, billed monthly; switch to yearly billing to save 20%. Cancel anytime, no contracts. Hitting a limit shows an upgrade link: no silent throttling and no overage charges. Start the Pro trial and pay $0 for 7 days; cancel before day 8 and you are never charged. Every plan only tests domains you have verified.
Keep load testing close to every release without turning it into a maintenance project.
Trigger tests from your deploy pipeline, release workflow, or internal automation with one API call. Stop building your own load testing tools — use a managed load testing service and start testing.
Release validation
Run a quick performance check before launch to catch regressions while the change is still easy to roll back or fix. Prevent slow releases by testing every deploy.
API confidence
Load test API endpoints, authentication flows, and critical user journeys with the same simple workflow every time.
Team visibility
Share result links in chat, tickets, or release notes so everyone can see the run without digging through logs.
Launch scaling
Validate scaling before product launches. Find bottlenecks in APIs and web apps quickly.
Shared perf view
Give engineering and product teams a shared performance view everyone can act on.
Know your application limits before production does.
Start your first free load test today. Infrastructure, scaling, and orchestration are already handled.
Can I use LoadTester for free load testing?
Yes. LoadTester includes a free plan for lightweight API and website load testing, so you can run real tests before deciding whether you need higher limits, CI/CD automation, scheduled runs, or regression detection.
Is LoadTester a load testing service or a tool?
It is both: a browser-based load testing tool delivered as a managed load testing service. You get the testing workflow, live results, thresholds, and exports without managing workers, dashboards, or test infrastructure.
Can I start load testing free?
Yes. Create a free account, configure a target URL, choose VUs or RPS, and run your first free load test from the dashboard. You can upgrade later only when you need more scale or automation.
Why use a load testing service instead of building it yourself?
A dedicated load testing service saves time, removes infrastructure overhead, gives you live analytics, supports CI/CD workflows, and makes it easier to repeat tests consistently. Instead of stitching together scripts, workers, dashboards, and thresholds, your team can run tests and act on results immediately.
Do I need to manage any infrastructure?
No. LoadTester handles execution infrastructure, scaling, and coordination so your team can focus on results instead of setup.
Can I use it for API and website load testing?
Yes. LoadTester works for API load testing, website load testing, HTTP endpoint testing, authentication flows, and broader application performance testing use cases.
Can I use it from CI/CD?
Yes. You can trigger tests from your pipeline, automate checks, and use thresholds to catch regressions before release. See our guide on load testing in CI/CD for patterns and examples.
Do you support auto-stop?
Yes. Configure thresholds for latency, failures, or other conditions and stop tests automatically when those limits are crossed.
Guides for choosing a free load testing service or tool.
Start with implementation guides when you are designing a test plan. Use the alternatives section when you are comparing LoadTester with CLI tools, open-source tools, or another managed load testing service.