---
title: "Frequently asked questions"
description: "Answers to the questions teams ask before adopting BabelQueue — broker support, wire-format stability, language and framework coverage, serialization overhead and cross-language tracing."
source: https://babelqueue.com/faq/
---

# Frequently asked questions

Everything teams ask before putting BabelQueue in front of a production queue — answered in
full, in one place. The normative detail lives in the wire contract at https://babelqueue.com/docs/spec/1.x/introduction/.

## Do I have to replace my message broker?

No. BabelQueue runs on the broker you already operate — it changes the serialization, not the transport. There is no new broker, sidecar or proxy to deploy.

## Which brokers are supported?

Seven, all GA and conformance-locked: Redis, RabbitMQ, Amazon SQS, Azure Service Bus, Apache Pulsar, Apache Kafka and Apache ActiveMQ/Artemis. The body is byte-identical on every one, so a message produced on one broker — or in one language — is consumed natively on another. Each broker ships across the SDKs (PHP × Azure Service Bus is the one documented exception).

## Will it change my existing (non-BabelQueue) jobs?

No. Standard framework jobs and workers stay exactly as they are. Only connections you opt into as polyglot use the canonical envelope, so adoption is incremental.

## Which languages and frameworks are supported?

All six SDKs are released at 1.0 and SemVer-stable: PHP (Laravel & Symfony), Python (Celery & Django), Go (Asynq & Machinery), Node.js (BullMQ & NestJS), Java (Spring Boot) and .NET (MassTransit) — each a framework-agnostic core plus a framework adapter, with per-broker transport modules on top.

## Is the wire format stable?

Yes. The envelope is frozen at schema_version 1: within that version the existing fields, their types and their meanings do not change — no field is renamed, removed or retyped, and the required fields keep their meaning. A new field may be added only as an optional, ignorable field, and only through an architecture decision record and an explicit version decision. A consumer that does not understand an unknown field must still process the message correctly and should preserve that field when it re-emits the message.

## How is a message identified across languages?

By a URN (urn:babel:<context>:<event>) carried in the envelope, never a class name — so a Go or Python consumer routes on a stable string without sharing any type with the producer.

## Is there a performance cost?

Negligible. The codec adds well under 2% over the plain-JSON serialization a publisher already pays, measured against a conservative broker round-trip — and it talks straight to native drivers, with nothing in between.

## How do I trace a message across services?

Every message carries a trace_id, generated by the first producer and preserved unchanged across every hop and language — so an end-to-end trace is one query away, no manual plumbing.