ST-2026-199 · Runtimes & developer platforms
Cloudflare Workers adds cross-language RPC between Python and JavaScript
Cloudflare made Python and JavaScript Workers interoperable through Workers RPC on 3 August 2026, allowing methods to be called across languages through Service bindings with structured-cloneable values and exception propagation across the call boundary.
Previous state
Workers RPC did not provide the announced direct Python-to-JavaScript and JavaScript-to-Python method interoperability through Service bindings.
Current state
Python and JavaScript Workers can call each other's methods through Workers RPC Service bindings, including structured-cloneable values and exception propagation across the language boundary.
Affected users
Who needs to care
Cloudflare Workers developers composing services across Python and JavaScript runtimes through Service bindings.
Required response
What to do
Validate service-binding interfaces, serializable value shapes and cross-language error handling before relying on the new interoperability in production workflows.
Evidence boundary
What the source does not prove
The source proves cross-language Workers RPC interoperability through documented Service bindings. It does not establish public-network RPC, cross-account availability beyond Service-binding rules, or removal of existing runtime and language constraints.
Lifecycle history
Dated event sequence
- Python and JavaScript Workers RPC interoperability becomes available
Cloudflare announced cross-language Workers RPC through Service bindings.
Evidence ledger
First-party sources
- 01Cloudflare — Python and JavaScript Workers can call each other over RPC
Official Cloudflare changelog · 2026-08-03
Open official source ↗