Compared with similar tools

Probe is a workflow runner, and testing and monitoring are two things you can do with it. Several tools sit nearby with different goals, and which one fits depends on what you are trying to do.

At a glance

	Kind	Written as	Operates on	Runs as
Probe	Workflow runner	YAML	HTTP, DB, SMTP, IMAP, SSH, shell, browser, gRPC	A single Go binary
k6	Load testing	JavaScript	HTTP, gRPC, WebSocket	A single Go binary
Postman / Newman	API testing	A GUI and its collections	HTTP	A GUI app and Node.js
Hurl	HTTP testing	Its own plain-text format	HTTP	A single Rust binary
Venom	Test runner	YAML	HTTP, SMTP, IMAP, SSH, SQL, gRPC and more	A single Go binary
runn	Scenario runner	YAML runbooks	HTTP, gRPC, DB, browser, SSH, commands	A single Go binary, or called from Go tests
Blackbox exporter	Probing for monitoring	A config file	HTTP, TCP, DNS, ICMP	A long-running process
GitHub Actions	CI	YAML	Whatever runs on the runner	GitHub’s runners
CWL / WDL	Describing computational pipelines	YAML or JSON (CWL), its own DSL (WDL)	Commands in containers, and files	Engines such as cwltool, Cromwell, miniwdl

Where each one differs

k6

k6 puts load on a system and measure what happens: concurrency, the distribution of response times. Probe has no way to generate load; it checks that one pass through a flow comes out right. Measure performance with k6.

Postman / Newman

Postman and its CLI, Newman , are HTTP-centred, and running them needs Node.js. Collections are a format meant to be edited in the GUI, which makes them awkward to read as a diff. Probe mixes other protocols into the same file, and the file is YAML you can review.

Hurl

Hurl is narrowed to HTTP, and within that range nothing is shorter to write. Probe covers more than HTTP, and pays for it in the job and step structure you have to spell out. For HTTP alone, Hurl is the lighter tool.

Venom

Venom is close too: YAML, several protocols, a single binary.

Two things differ. Probe declares dependencies between jobs with needs and can print that graph with probe dag. And repeat runs the same file on an interval and reports a success rate, which is what lets a file written as a test serve as a monitor.

runn

runn is another of the closest. Scenarios in YAML, with HTTP, gRPC, databases, a browser, SSH and commands available in the same file. It evaluates expressions with expr, as Probe does, so what you can write in test reads much the same.

Three things differ. runn walks a runbook from top to bottom, where Probe schedules whole jobs in parallel and declares the order with needs. runn can be called from Go test code as a test helper, where Probe is a CLI. And Probe’s actions are separate processes behind go-plugin, so one can be added without touching the binary.

Blackbox exporter

Blackbox exporter repeats single probes for monitoring, built to be scraped by Prometheus. It does not carry a multi-step flow — signing in, taking a token, passing it to the next request. Probe writes that flow, but has nothing that collects and stores metrics.

GitHub Actions

The notation of GitHub Actions is close: jobs, steps, needs, uses and with line up with Probe almost one for one. But it runs on GitHub’s runners, so you cannot run it from your own terminal or see the dependency graph. Probe behaves the same way in CI and on your machine.

CWL / WDL

The same word, a different subject. The Common Workflow Language and the Workflow Description Language are specifications for describing computational pipelines, used in bioinformatics and other research fields.

A step runs a command inside a container and takes files in and out. The order is not declared the way needs declares it: it falls out of connecting one step’s output to another’s input. What runs them is not the specification but an engine — cwltool, Cromwell, miniwdl — usually against an HPC scheduler or a cloud batch service.

Probe touches a running system and checks what it answers; it is not a pipeline for transforming data. Feeding a lot of files through a series of stages is not what it is for.

A caveat

This comparison reflects how these tools were built as of September 2026. They all keep moving, so check each project’s current documentation before deciding.