Try fpstreams in your browser

Edit an example and run it in your browser. The page downloads Python and the fpstreams pure-Python wheel, then runs your code in a separate worker. It does not send your code to an fpstreams server. The first load can take longer while the runtime downloads.

Runs locally in your browser

Run a Python pipeline

Loading Python runtime…

Flow Rows Group + join Pairs AsyncFlow

Python Ctrl/⌘ + Enter

Python source code

Variables stay available between runs. Reset runtime clears them and starts Python again.

Execution output idle

result

Run the example to see its value.

Run code Stop Reset runtime Python 3.14 · fpstreams pure-Python engine

Browser scope

You can try the core APIs here:

• Flow, Rows, Pairs, collectors, expressions, and AsyncFlow run locally;
• the auto engine selects the canonical Python path because the CPython/Rust extension is not a WebAssembly wheel;
• stopping code terminates the worker, including an accidental infinite loop;
• local operating-system paths, process pools, and native-only execution are not available inside the browser sandbox;
• the runtime and wheel are fetched from the network on first use. Resetting the runtime downloads them again when they are not already in the browser cache.

For production workloads, install the regular package to gain Rust acceleration, filesystem access, optional data-system adapters, and normal profiling tools.