Subtrace is a network inspector for a backend — an open-source, Go-based command-line tool under the BSD-3-Clause licence that inspects HTTP requests in any server with just a single command.

What it is

Subtrace sits in the Infrastructure & Operations / Monitoring & Observability category of this registry. It is written in Go, carries the GitHub topics backend, devtools, monitoring and observability, and is published under the BSD-3-Clause licence. The repository at the time of writing shows 3,099 stars, 86 forks and 15 open issues, with the most recent push on 28 January 2026. Its homepage is https://subtrace.dev, and the README describes it as a network inspector for your backend.

The problem it addresses is the cost of getting HTTP-level visibility into a server that is already running. The README does not name a competing tool that Subtrace replaces. What it replaces is the invocation itself: instead of starting a server directly, the developer runs the same command under subtrace run. The tool is framework-agnostic within that pattern, and the README demonstrates it against Node.js, FastAPI, and a catch-all "everything else" case expressed as subtrace run -- [command]. The ecosystem it lives in is therefore the developer's own local and containerised runtime, not a language-specific middleware layer.

Key capabilities

• Starts inspection from a single wrapper command, subtrace run -- [command], rather than through code changes to the server.
• Documented against Node.js via subtrace run -- npm run dev and against FastAPI via subtrace run -- fastapi dev main.py.
• Handles arbitrary runtimes through the generic form subtrace run -- [command], which the README labels "Everything else".
• Installs on Linux with a single shell command: curl -fsSL https://subtrace.dev/install.sh | sh.
• Ships dedicated deployment guides for Docker, Docker Compose and Kubernetes at https://subtrace.dev/docs.
• Provides reference documentation at https://subtrace.dev/docs and a community Discord at https://subtrace.dev/discord.
• Is distributed under the BSD-3-Clause licence, so the source can be read, modified and redistributed under those terms.

Who uses it and how

• Backend developers on Linux who want HTTP request visibility from an existing development server without editing application code.
• Node.js teams running npm run dev as their normal local loop and wrapping that same command to gain inspection.
• Python teams running FastAPI through fastapi dev main.py as the entry point for a development server.
• Teams operating containerised services, using the Docker and Docker Compose guides to place inspection alongside existing service definitions.
• Platform and infrastructure teams running workloads on Kubernetes, using the Kubernetes guide to deploy inspection in a cluster.

Getting started

On Linux, install with curl -fsSL https://subtrace.dev/install.sh | sh, then run a server under inspection with subtrace run -- npm run dev, subtrace run -- fastapi dev main.py, or subtrace run -- [command] for anything else.

How it compares

This registry provides no list of paid products that Subtrace replaces, and the facts name no similar tool. Subtrace therefore stands alone in this registry on that axis. The only comparison surface the supplied facts support is platform coverage: Linux is generally available, while macOS is in private beta.

When to use it — and when not to

Choose Subtrace when the work happens on Linux, the server already starts from a command line, and inspection is wanted without touching application code. Do not choose it when macOS is the primary development environment, because that platform is in private beta and access requires joining the waitlist at https://mac.subtrace.dev. A Windows path is not documented in the supplied facts, and the README is short: it lists installation, quickstart commands and guide links, but no architecture or operational detail, so teams needing deep documentation before adoption should read the linked docs first.

curl -fsSL https://subtrace.dev/install.sh | sh

# Node.js
subtrace run -- npm run dev

# FastAPI
subtrace run -- fastapi dev main.py

# Everything else
subtrace run -- [command]