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Superbenchmarker is a command-line load generator tool for performance testing HTTP APIs and websites. Inspired by Apache Benchmark, it is meant to become Apache Benchmark (ab.exe) on steriods. It displays final results at the end of the test in the terminal window but it also constantly reports back in a web interface.


Gettting Started

What you need

Superbenchmarker (sb or sbcore) runs on Windows or Mac (not tested yet on Linux) and requires .NET 4.52+ or .NET Core 2.1+ installed on the box.

Installation - Windows

Easiest way to install sb is to use chocolatey.

SuperBenchmarker (built on .NET 4.5.2)

> cinst SuperBenchmarker

and to update your version of sb:

> cup SuperBenchmarker

In this release, use sb to run SuperBenchmaker:

> sb

NEW! SuperBenchmarkerCore (built on .NET Core 3.1)

> cinst SuperBenchmarkerCore

and to update your version of sb:

> cup SuperBenchmarkerCore

In this release, use sbcore to run SuperBenchmaker:

> sbcore

You can also download the lastest version from the Download folder of this github repository. This is a single exe with all dependencies IL-merged.

Installation - Mac

Currently, until brew is sorted out, you need to build from the source:

git clone
cd SuperBenchmarker

And then you can run using dotnet command:

dotnet ./src/SuperBenchmarker/bin/Debug/netcoreapp2.0/SuperBenchmarker.dll -u -N 10

Running it and basic command parameters

To run it, just point it to a website or API using -u (--url) parameter (NOTE: In all these examples, if you have installed SuperBenchmarkerCore, replace sb with sbcore):

sb -u ""

This command fires 100 GET requests using a single thread, which is equivalent to running command below:

sb -u "" -c 1 -n 100

So you can use -c and -n to change concurrency or total number of requests. Be careful not to use a very high -c on a single box since it will affect the result of the test. Watchout for CPU consumption on the box and make sure it is < 70%.

In order to run your test for a period of time rather than total number of requests, use -N to specify number of seconds. Command below runs the test for half an hour:

sb -u "" -c 4 -N 1800

You can use -c to increase and -y (delayInMilliseconds) to decrease in order to control the load on your server and achieve the desired throughput.

To use a different HTTP verb, use -m (--method) parameter:

sb -u "" -n 1000 -m DELETE

To dry-run a particular set-up you can use -d (--dryRun) which fires a single requests and outputs the result.

Taking it to the next level

Send custom headers/payload to the API

In order to send custom headers (or payload), you need a template file. A template file is a text file which - similar to HTTP - has headers and values in each line, then an empty line, and in the end the payload (assuming you are sending a text payload).

For example, to send an Authorization header to the server, create a text file called template.txt with this content:

Authorization: Basic GV5ITpub3Bhc3N3b3JkaGVyZQ==

And then run it using -t (--template):

sb -u "" -n 1000 -t template.txt

Another example, to make a POST request sending a JSON payload, create this file (NOTE the empty line between headers and body):

Content-Type: application/json

    "foo": "bar"

Parameterise the requests

It is all well and good to keep sending the same request but in order to truly test your application, you would need to make different requests. You can parameterise the URL and the template. Parameters are defined by triple curly braces:

sb -u "{{{carId}}}"

in the above, we defined a parameter named carId. sb has built-in support for sending random STRING, DATE, DATETIME, DATETIMEOFFSET, INTEGER, DOUBLE, NAME and GUID - and for some data type it can do ranges. For example:

sb -u "{{{carId:RAND_INTEGER:[1:1000000]}}}"

sends random integers in the range of 1 and 1,000,000.

Of course, random values do not always work and data needs to be taken from a pool of known values. In this case you can create a data file containing headers, matching the parameter names you have. (By default, only URL will be parameterised and if you need to parameterise the body too, you need to add flag -b too(. You pass the name of the file using -f (file) which assumes the file is a CSV. You can shuffle the records using -U (--shuffleData) flag. TSV is also supported using option -a (--TSV), here with shuffling the data:

sb -u "{{{carId}}}" -f carIds.tsv -a -U

Let's look an example. So let's say you are testing car update API (which needs a PUT method with a payload) and you need to parameterise car id and their prices. Prepare a data file called testdata.csv:


And create a template file (template.txt):

some-header: some-value

    "price": {{{price}}}

And now run your test. NOTE that -b needs to be supplied to parameterise body:

sb -u "{{{carId}}}" -f testdata.csv -t template.txt -m PUT -b

Values from your dataset will be used to populate and send requests. Once it has reached the end of the file, it will start from the beginning.

You can also create a data provider plugin to fully control the process. See below for more information.

Real-time report chart/UI

Soon after running the test, your browser will be directed to a file which gets updated in real-time with the progress of your test. In case you do not this to happen, simple use -B (--dontBrowseToReports) flag. If you have used -B flag and but then changed your mind and you decide to see the progress, simply browse the file index.html in subfolder (inside the execution folder) with a name representing timestamp the test started (e.g. 2018-02-16_10-12-53.898088). If you would like to change the name, use -F option and provide an alternative folder name.

This folder, after the test finishes, will contain all information you need about your test. You can simply zip it up and keep it for archiving, and go back it to when you need to. The folder contains an interim.js file while the test is running and gets replaced with the "final.js" after the test finishes. These files contain the data powering charts.

Interacting with the chart is straightforward. The chart gets updated every 3 seconds and the thickness of the cyan vertical line shows the precision of mouse movements for navigating the chart. As more data arrives, the vertical line gets thinner, i.e. more precision. You can pause/unpause the chart update by clicking on the chart.

The data slices are taken every 3 seconds. You can change it by using option -P (--reportSliceSeconds). For short burst tests perhaps using one second is more appropriate (-P 1):

sb -u " -N 60 -P 1

Parameters to control terminal output

The terminal output is by no means a second class citizen. For debugging purposes that is the best option, e.g. to be able to see the request, headers, etc. Bear in mind, outputting more content to the terminal can impact the test results hence only useful for debugging.


Here are options to control the output:

  • -v (--verbose): outputs verbose
  • -h (--headers): output headers
  • -k (--cookies): output cookies
  • -q (--onlyRequest): outputs only request information

Capturing response information

At a minimum, you will be interested in the response time and status code. sb already provides a detailed breakdown both in the terminal output and in its report. However, sometimes you would like to dig deeper or know which requests failed and in these cases, what were the value of the parameters sent to the server.

sb logs all such information in its run.log file, stored inside the folder where the report files get stored (see above). You may change the name of the file or its location using -l (--logFile) option, passing the file name (or full path to change the location). This file is a non-headered tab-separated TSV which contains these columns:

  • datetime - after which the response received and its body consumed
  • index of the request (they can be out of order)
  • numeric value of the HTTP status code
  • time taken in millisecond
  • one column per each parameter in the format of <name>=<value>. These parameters include jsonCount or regex extraction (see below). By default, value of the parameter is truncated and capped to 50 characters. To prevent that, use flag -C (--dontcap)

Sometimes you might be interested to save the whole response body. In this case, use flag -z to store responses in "responses" subfolder. If you would like to store in another folder, use -w:

sb -u "" -z -w "anotherFolder"

Occasionaly, all you need is a small piece of information out of the response body. For example, you would like to see how many records returned in the JSON response. You can use option -j (--jsonCount) with the tree location of element containing array. For example, in this JSON response:

    "foo": {
        "bar": [

the array is located at path "foo/bar" and you would use this command to capture the count in the run.log:

sb -u "" -j "foo/bar"

if the result from the server itself is an array at the root, use empty string as the path:

sb -u "" -j ""

Sometimes you would like to capture part of the response body. You can use option -R to provide a regex to capture the substring of interest. You would use a regex with one group, denoting the value to capture. For example, let's imagine result is an HTML:

Your ID is: 12313554

you would use the commadn below to capture the ID in the log file:

sb -u "" -R "Your ID is: (\d+)"

Other options

Connection options: proxy and TLS

Use -x if you need the client to use default proxy. Using option -g you can set the TLS version. For example, to use TLS 1.2:

sb -u "" -g 2


You can use -W option to provide number of seconds for warmup where the results are not included in the test.

Plugin development

Not all features can be done via command line parameters and sometimes more flexibility is needed that must be done via a plugin. SuperBenchmarker provides plugin interfaces for these two scenarios:

  • full control over parameterisation (instead of providing a CSV or TSV)
  • Overriding HTTP Status Code. There are some APIs that return 200 and the success is determined by the content.

In order to build a plugin, just add a reference to sb.exe in chocolatey lib folder (if you have installed .NET Core package, add a reference to superbenchmarker.dll) and build your DLL.

parameterisation (IValueProvider)

You need to include in your DLL a public class implementing IValueProvider. SuperBenchmarker search through public types in the DLL and if it finds an implementation of IValueProvider, it uses it.

public class MyPlugin: IValueProvider
    private IList<string> _ids; // e.g. populated from a database
    public IDictionary<string, object> GetValues(int index)
        // return a dictionary with name of the parameters and their corresponding values.
        // index is the 0-based count of the requests sent. For example, if index is 9, it is the 10th request
        return new Dictionary { {"ID", _ids(index)} };

Overriding HTTP Status (IResponseStatusOverride)

You need to include in your DLL a public class implementing IResponseStatusOverride. SuperBenchmarker search through public types in the DLL and if it finds an implementation of IResponseStatusOverride, it uses it.

public class TeaPot : IResponseStatusOverride
    public HttpStatusCode OverrideStatus(HttpStatusCode statusReceived, 
        byte[] responseBuffer, 
        HttpResponseHeaders responseHeaders,
        HttpRequestMessage request)
        // look into response buffer (byte array) and then return a status
        return (HttpStatusCode) 418;

Running with the plugin

Then run this commmand (NOTE name of the parameter returned in the dictionary is the same as the one defined below):

sb -u "{{{ID}}}" -p c:/path/to/my/plugin/myplugin.dll

Bear in mind, in most cases you need to pass the full path to the DLL.


  -c, --concurrency            (Default: 1) Number of concurrent requests

  -n, --numberOfRequests       (Default: 100) Total number of requests

  -N, --numberOfSeconds        Number of seconds to run the test. If specified, -n will be ignored.

  -y, --delayInMillisecond     (Default: 0) Delay in millisecond

  -u, --url                    Required. Target URL to call. Can include placeholders.

  -m, --method                 (Default: GET) HTTP Method to use

  -t, --template               Path to request template to use

  -p, --plugin                 Name of the plugin (DLL) to replace placeholders or override HTTP Status.
                               Should contain one class implements IValueProvider or IResponseStatusOverride. 

  -l, --logfile                Path to the log file storing run stats

  -f, --file                   Path to CSV file providing replacement values for the test

  -a, --TSV                    If you provide a tab-separated-file (TSV) with -f option instead of CSV

  -d, --dryRun                 Runs a single dry run request to make sure all is good

  -e, --timedField             Designates a datetime field in data. If set, requests will be sent according to order
                               and timing of records.

  -g, --TlsVersion             Version of TLS used. Accepted values are 0, 1, 2 and 3 for TLS 1.0, TLS 1.1 and TLS 1.2
                               and SSL3, respectively

  -v, --verbose                Provides verbose tracing information

  -b, --tokeniseBody           Tokenise the body

  -k, --cookies                Outputs cookies

  -x, --useProxy               Whether to use default browser proxy. Useful for seeing request/response in Fiddler.

  -q, --onlyRequest            In a dry-run (debug) mode shows only the request.

  -h, --headers                Displays headers for request and response.

  -z, --saveResponses          saves responses in -w parameter or if not provided in\response_<timestamp>

  -w, --responsesFolder        folder to save responses in if and only if -w parameter is set

  -?, --help                   Displays this help.

  -C, --dontcap                Don't Cap to 50 characters when Logging parameters

  -R, --responseregex          Regex to extract from response. If it has groups, it retrieves the last group.

  -j, --jsonCount              Captures number of elements under the path e.g. root/leaf1/leaf2 finds count of leaf2
                               children - stores in the log as another parameter

  -W, --warmUpPeriod           (Default: 0) Number of seconds to gradually increase number of concurrent users. Warm-up
                               calls do not affect stats.

  -P, --reportSliceSeconds     (Default: 3) Number of seconds as interval for reporting slices. E.g. if chosen as 5,
                               report charts have 5 second intervals.

  -F, --reportFolder           Name of the folder where report files get stored. By default it is in
                               yyyy-MM-dd_HH-mm-ss.ffffff of the start time.

  -B, --dontBrowseToReports    By default it, sb opens the browser with the report of the running test. If specified,
                               it wil not browse.

  -U, --shuffleData            If specified, shuffles the dataset provided by -f option.

  --help                       Display this help screen.


Apache Benchmark (ab.exe) on steroids







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