What is Siege?
Siege is an open-source HTTP regression testing and benchmarking tool, available since the early 2000s. It's a Unix CLI written in C, multi-threaded, and reads URLs from a file (the "urls.txt") to hit them with concurrent users at configurable rates. Siege is widely used by operations teams for "is this server holding up under load" sanity checks.
Siege runs from one machine, prints results to stdout when the test ends, and ships with a small set of options for concurrent users, duration, and request rate. It's intentionally simple, designed for quick benchmarks rather than complex scenario testing.
When Siege is the right tool
Siege fits these workflows:
- Quick HTTP regression checks. "Did my server config change degrade performance?". Siege runs a quick benchmark against a URL list and reports basic metrics.
- Single-machine availability tests. Soak a URL with a fixed concurrency for a duration and confirm it doesn't fall over.
- CI smoke load tests. Wrap Siege in a shell script for "does the deployment respond under any load at all" CI checks.
- Sysadmin tooling. Siege is part of many Linux distros' standard package repositories, easy to install, no dependencies.
Where Siege stops being enough
Siege's simplicity is its strength and its limit. Real load testing programs need capabilities Siege doesn't have:
- Single-machine capacity ceiling. Network and CPU on one machine cap your VU/RPS counts. Real-world high-traffic simulation requires distributed tools.
- No GUI, no historical view. Stdout-only output. Trending, comparing runs, and sharing with stakeholders requires custom tooling.
- No geographic distribution. Tests run from wherever you launch Siege.
- Limited scenario complexity. Siege hits URLs from a list. Multi-step user flows, custom request bodies, response assertions, and dynamic data require switching tools.
- No API monitoring or page speed monitoring. Siege is HTTP load testing only.
LoadFocus vs Siege: feature comparison
The table below compares LoadFocus against Siege in typical usage. Siege is open-source (free); the comparison is on capability.
| Feature | LoadFocus | Siege |
|---|---|---|
| Cost | Free tier; from $29/mo | Free (open-source) |
| Deployment model | Cloud SaaS | Self-hosted CLI |
| Web UI | Yes | No (terminal only) |
| Distributed execution | Yes (managed) | Manual (multi-instance) |
| Geographic test coverage | 25+ cloud regions | Wherever you run it |
| Max throughput | Up to 12,500 VUs | Bounded by single machine |
| JMeter (.jmx) script support | Yes (native) | No |
| k6 (.js) script support | Yes (native) | No |
| Multi-step scenario support | Yes | Limited (URL list only) |
| Response assertions | Yes | No |
| Historical results + trend graphs | Yes | No |
| CI/CD integration | Yes (CLI + GitHub Action) | Manual (shell + parsing) |
| AI-generated analysis | Yes (all plans) | No |
| Page speed monitoring | Yes | No |
| API monitoring | Yes | No |
When LoadFocus is the right upgrade from Siege
Siege is good for what it's designed for. The decision to move comes when you need anything beyond single-machine HTTP benchmarks.
You need geographic distribution
Single-machine Siege measures from your one launch point. Real users hit your service from many regions; LoadFocus surfaces regional differences from 25+ regions.
You need to scale beyond one machine
Siege's capacity is bounded by your launching machine. For tests requiring 5,000+ concurrent users, distributed tools handle this transparently.
You need multi-step scenarios with assertions
Siege hits URLs from a list. For tests like "log in, browse to a product, add to cart, checkout" with assertions at each step, you need k6 or JMeter scripting.
You want a UI, history, and shareable reports
Siege's terminal output is engineer-friendly. For QA, product, and SRE stakeholders, LoadFocus's UI and persistent dashboards are easier to consume.
You want consolidated load + page speed + API monitoring
Siege does HTTP load testing. LoadFocus combines load + page speed + API on one platform.
Migration from Siege
- Sign up at loadfocus.com/signup.
- Translate your Siege URL list to a k6 (.js) or JMeter (.jmx) script. For URL-list tests, k6 is closest: a loop of
http.get(url)calls in adefaultfunction. - Upload the .js or .jmx to LoadFocus.
- Configure VU count and duration to match your Siege parameters.
- Run from one or more regions. Compare results against your Siege runs to validate.
Many sysadmin teams keep Siege for quick local sanity checks and use LoadFocus for distributed/scheduled tests with historical reports. The two coexist well.
FAQ: LoadFocus vs Siege
Is Siege faster than LoadFocus?
For raw single-machine HTTP throughput, Siege and tools like wrk are competitive. LoadFocus's strength isn't single-machine speed, it's distributed cloud execution, UI, history, and integration. For peak RPS from one box, Siege wins; for everything else, LoadFocus is the right tool.
Can I use Siege URL files in LoadFocus?
Not directly. The closest equivalent is a k6 script that iterates an array of URLs. Translating a Siege urls.txt to a k6 script is straightforward, typically under 10 lines of JavaScript.
How does pricing compare?
Siege is open-source (free). LoadFocus starts at $29/month with a free tier. The cost trade-off is whether you value cloud execution, UI, history, and integration enough to pay for them.
Can I keep Siege and add LoadFocus?
Yes. Many ops teams keep Siege for quick local benchmarks and add LoadFocus for distributed/scheduled tests with persistent results.
Does LoadFocus replace Siege for sysadmin sanity checks?
For quick "does the server respond under load" tests from your laptop, Siege remains faster to use. For team-wide test programs with history and stakeholder reports, LoadFocus is the better fit.
Try LoadFocus free
If Siege has been your go-to for quick HTTP benchmarks but you've hit its single-machine ceiling or need persistent history, LoadFocus extends that model into managed cloud execution. Sign up for a free tier at loadfocus.com/signup, no credit card, and run your first cloud HTTP load test in under 5 minutes.
