Compatibility
This matrix is based on the public implementation repositories plus maintainer interoperability runs. For the current result counts, see VALIDATION.md.
Statuses:
Tested: directly covered by the current validation snapshot.Supported: documented or directly represented in source/tests, but not necessarily covered by the current cross-runtime snapshot.Partial: implemented or partly tested, with known coverage or host-environment limits.Planned: described as future work.Not applicable: the feature does not apply to that implementation type.Implementation-specific: the concept exists but behavior depends on host/framework usage.Unknown: not enough evidence to make a public claim.
Validation Highlights
Last updated: 2026-06-13.
| Area |
Result |
| Cross-runtime HTTP interoperability matrix |
36/36 client/server combinations passed; fail=0 gap=0 |
| Express Safe Mode baseline |
pass=13 fail=0 |
| Node core HTTP Safe Mode |
pass=16 fail=0 gap=0; unit tests 8 passed |
| .NET interoperability |
.NET client to all matrix servers passed; all matrix clients to .NET server passed; unit tests 60 passed |
| Java interoperability |
Java client to all matrix servers passed; all matrix clients to Java server passed; full Gradle test suite passed |
| Android Java runtime |
rpc-android instrumentation tests on Samsung SM-T733, Android 14/API 34: 4 passed over adb reverse; 4 passed over direct WiFi/LAN |
| PHP interoperability |
PHP client to all matrix servers passed; all matrix clients to PHP server passed |
| Python interoperability |
Python client to all matrix servers passed; all matrix clients to Python server passed; unit tests 12 passed |
| Arduino ESP32 physical runtime |
Node client to ESP32 WiFi server pass=21 fail=0 gap=0; ESP32 board-to-board heap run captured |
| Arduino ESP8266 physical runtime |
ESP8266 WiFi client to Express Safe endpoint pass=21 fail=0 gap=0; ESP8266 WiFi client to ESP32 server pass=21 fail=0 gap=0 |
| Node-RED integration |
Docker runtime probe pass=27 fail=0; public Flow Library scorecard pass=12 warn=0 fail=0 |
HTTP Interoperability Matrix
The matrix below uses the shared Safe Mode HTTP contract and was run on 2026-06-13. Servers: rpc-express-toolkit, rpc-node-toolkit, rpc-dotnet-toolkit, rpc-java-toolkit, rpc-php-toolkit, and rpc-python-toolkit.
| Client |
Express |
Node |
.NET |
Java |
PHP |
Python |
| Raw HTTP probe |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
| JS client |
PASS (9/0) |
PASS (9/0) |
PASS (9/0) |
PASS (9/0) |
PASS (9/0) |
PASS (9/0) |
| .NET client |
PASS (17/0) |
PASS (17/0) |
PASS (17/0) |
PASS (17/0) |
PASS (17/0) |
PASS (17/0) |
| Java client |
PASS (17/0) |
PASS (17/0) |
PASS (17/0) |
PASS (17/0) |
PASS (17/0) |
PASS (17/0) |
| PHP client |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
| Python client |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
PASS (14/0) |
Protocol And Payload Features
| Feature |
JS Client |
Node |
Express |
Python |
PHP |
.NET |
Java |
Arduino |
Node-RED |
| JSON-RPC 2.0 envelope |
Supported |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
| Object params |
Supported |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
| Array params |
Supported |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
| Batch requests |
Supported |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Supported |
Tested |
| Notifications |
Supported |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
| Error responses |
Supported |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
error.data |
Supported |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Safe Mode And Introspection
| Feature |
JS Client |
Node |
Express |
Python |
PHP |
.NET |
Java |
Arduino |
Node-RED |
| Safe Mode |
Supported |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested on ESP32/ESP8266 WiFi |
Tested |
| Safe Mode strict mode |
Supported |
Tested |
Tested |
Tested |
Tested |
Tested |
Partial |
Tested on ESP32/ESP8266 WiFi |
Tested |
| Introspection |
Not applicable |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
Tested |
| Schema metadata |
Not applicable |
Tested |
Tested |
Tested |
Tested |
Tested |
Partial |
Supported |
Tested |
| Runtime schema validation |
Not applicable |
Tested |
Tested |
Tested |
Tested |
Tested |
Unknown |
Planned |
Tested |
Transports And Integration
| Feature |
JS Client |
Node |
Express |
Python |
PHP |
.NET |
Java |
Arduino |
Node-RED |
| HTTP transport |
Supported |
Tested |
Tested |
Tested |
Implementation-specific |
Tested |
Tested |
Tested on ESP32/ESP8266 WiFi |
Tested |
| Serial transport |
Not applicable |
Not applicable |
Not applicable |
Not applicable |
Not applicable |
Not applicable |
Not applicable |
Supported |
Not applicable |
| Authentication middleware/hooks |
Not applicable |
Implementation-specific |
Supported |
Implementation-specific |
Supported |
Supported |
Supported |
Not applicable |
Supported |
| Method whitelist |
Not applicable |
Unknown |
Supported |
Unknown |
Supported |
Unknown |
Unknown |
Unknown |
Unknown |
| Node-RED integration |
Client-compatible |
Client-compatible |
Client-compatible |
Client-compatible |
Client-compatible |
Client-compatible |
Client-compatible |
Client-compatible |
Tested |
| Embedded support |
Client-compatible |
Client-compatible |
Client-compatible |
Client-compatible |
Client-compatible |
Client-compatible |
Client-compatible |
Tested on ESP32/ESP8266 WiFi; ESP8266 build-tested |
Client-compatible |
Notes
rpc-arduino-toolkit has captured physical WiFi runtime evidence on ESP32 and ESP8266. The current snapshot includes Node client to ESP32 server, ESP8266 client to Express, and ESP8266 client to ESP32 server runs.rpc-python-toolkit has client/server Safe Mode interoperability evidence and unit-test coverage in the current validation snapshot.rpc-java-toolkit includes Android client runtime evidence through physical rpc-android instrumentation tests on Android 14/API 34, including both adb reverse and direct WiFi/LAN endpoint runs.rpc-toolkit-js-client is a client library, so server-side features such as introspection hosting and runtime validation are not applicable.node-red-contrib-rpc-toolkit integrates RPC endpoints into Node-RED flows and delegates core HTTP behavior through the Node-RED runtime and rpc-express-toolkit. Docker runtime probe and public Flow Library scorecard are green.- Java strict HTTP Safe Mode header handling is a wrapper-level concern in the tested server because the Java core endpoint is transport agnostic.