End-to-end prototype/demo for browser SDK

[martinkuba]

Summary

We've been asked multiple times to build a working end-to-end prototype that demonstrates how we imagine OTel to work in browser environments. Rather than continuing to iterate on spec text alone, the goal is to have something tangible and runnable that proves out the key design decisions.

As discussed in the Browser SIG on 2026-03-19, I'd like to collaborate on this with anyone who's interested.

What the prototype should cover

Initial focus

1. Mutable resource / entity swapping
   Sessions (and potentially other things) modeled as entities that can change at runtime, with all instrumentations transparently picking up the current entity
2. Multiple simultaneous entities -
   for example, session and page view coexisting in the resource with independent lifecycles
3. Events instead of metrics (with collector-side aggregation)
   No metrics SDK on the client; events sent to a collector that aggregates them into metrics.
4. SDK configuration layer
   A simplified configuration entry point for users with sensible defaults

Secondary

5. Protocol optimization exploration — Investigating lighter-weight transport from browser to collector (simpler JSON, dictionary-based compression, schema URL references, etc.)
6. API - optimized for client/browser applications
   Explore whether browser/mobile needs a dedicated API surface beyond the standard OTel API

Architecture

Should have

• browser SDK/instrumentations
  • already available + features we would like to explore and propose for spec
• sample app
  • instrumented with our recommended instrumentations
• collector
  • including a connector that generates metrics from events
• backend
  • for example Grafana LGTM stack

Background & references

• OTEP: Allow multiple Resources in an SDK
• OTEP: Define EntityProvider
• Browser prototype for sessions as entities
• configuration helper functions for web (prior attempt)
• Android agent API

Call for collaboration

If you're interested in working on any part of this, please comment here.

[martinkuba]

The configuration layer was also included in this prototype
https://github.com/open-telemetry/opentelemetry-browser/pull/170/changes#diff-cebcacc28707689941625c683e22a28dc564531f3c82ed641efe0a87c24791e9

[mquentin]

Hey, so I am in to help on this effort !
One thing that could be great to demo end-to-end this browser SDK is a playground demo app (thanks @BenoitZugmeyer for this great idea btw).

The concept is a static app that can be hosted in a github page that:

• initialize the prototype SDK with all the main processor and instrumentations
• find a way to provide a custom intake URL if users what to actually send the Demo OTel signals to any intake (maybe a URL query param of the page, or a small form in the page)
• has a set of UI button that triggers some RUM OTel signals like

It helps documenting two main things:

• how to configure the SDK and what are the options
• what are the supported feature at the moment

What do you think about this ?

[mquentin]

As a matter of fact, I worked on a small prototype here: https://mquentin.github.io/otel-browser-sdk-demo let me know what you think about it.

[joaquin-diaz]

I'll be working on adding the collector and backend for this

[martinkuba]

I have created this branch for this
https://github.com/open-telemetry/opentelemetry-browser/tree/prototype/browser-e2e-demo