TagPiper replicates Google sGTM's sandboxed template API, on a 4 MB image you host yourself, with a built-in debugger.
Four reasons, from learning how server-side tagging really works to owning every line of it.
Rebuilding the Google sGTM model from scratch is the best way to understand exactly how server-side tagging works.
Less CPU and memory per hit means fewer, smaller servers. TagPiper is a 4 MB image that idles at about 7 MiB.
Anything can go straight into the server, in Rust, without waiting for a vendor. Examples: send queues, retries and SSRF protection.
Every line that handles your visitors' data can be read, and every outgoing request can be seen and counted.
Measured on the published image, with Docker limited to one CPU and 256 MB.
/healthz requests per secondReal-usage benchmarks are coming. The numbers above measure the HTTP layer only. Benchmarks with real GA4 traffic through clients and tags, and a side-by-side comparison with Google sGTM, will follow. See the benchmarks.
A self-hosted web app, built with Nuxt 4, Tailwind and PostgreSQL. It keeps your configuration, so the servers that handle your traffic stay lightweight.
Create containers, add clients and tags, and configure their fields. Import your Google sGTM templates.
Decide which tags fire for which events, with reusable variables and lookups.
Follow hits and tag results over time, and watch every server's health: CPU, memory, queue and delivery.
Publish container versions, see what changed, and inspect any single hit from end to end.
If you've used Google sGTM, you already know the model. TagPiper runs the same model on a lightweight server you control.
A browser or app sends a hit, such as a GA4 /g/collect request, to your TagPiper endpoint on your own domain.
Each client template gets a turn with the request. The one that claims it builds the event data and calls runContainer.
Tags get each event and send it on. The browser gets its response right away, and the sends are delivered and retried in the background.
Pull the image, start it with the playground on, and open it in your browser.
docker run --rm -p 8080:8080 --cpus=1 --memory=256m \
-e PORT=8080 -e PLAYGROUND=1 -e OUTGOING_DRY_RUN=1 \
ghcr.io/tagpiperlabs/sst-server:latest
# then open http://localhost:8080/This site is plain Markdown on GitHub. Every page has an “Edit this page” link.
TagPiper Labs on GitHub