Cloud Pub/Sub API
Cloud Pub/Sub API
Google Cloud Pub/Sub API is a globally-scaled message queue — topic/subscription model, at-least-once delivery, millisecond latency, auto-scaling.
Global-scale — single topic supports cross-region publish/subscribe
No strict message ordering by default (Pub/Sub Lite provides it)
POST /v1/projects/{projectId}/topics to create a topic; POST /v1/projects/{projectId}/subscriptions to create a subscription. Publishers call publish; subscribers pull or receive via push endpoint.
Uptime · 30-day window
About this API
Pub/Sub is GCP's messaging middleware — comparable to AWS SNS+SQS combined or Kafka's managed version, with its own twist: fully serverless, global-scale topics (a message can publish/subscribe across continents), billed by message count and bytes. Design is "at-least-once" — messages are delivered but may be duplicated — so consumers must be idempotent. Pub/Sub is the glue in GCP data pipelines: a typical architecture is producer → Pub/Sub → Dataflow (processing) → BigQuery (storage), fully managed with no ops burden. Compared to Kafka, it lacks strict ordering and long-term replay capabilities, but ops is much simpler. GCP also offers Pub/Sub Lite, which provides Kafka-like strict ordering at the cost of global-scale.
What you can build
- 1Inter-microservice async communication
- 2Event bus (order creation → multiple downstream handlers)
- 3Data pipeline (Pub/Sub → Dataflow → BigQuery)
- 4Device telemetry upload
Strengths & limitations
Strengths
- Global-scale — single topic supports cross-region publish/subscribe
- At-least-once delivery guarantee
- Auto-scaling, no broker management
- Native integration with Dataflow / Functions / Cloud Run
Limitations
- No strict message ordering by default (Pub/Sub Lite provides it)
- Per-message size limit 10MB
- At-least-once delivery requires consumer-side idempotency
Example request
curl https://google.com/<endpoint>Getting started
POST /v1/projects/{projectId}/topics to create a topic; POST /v1/projects/{projectId}/subscriptions to create a subscription. Publishers call publish; subscribers pull or receive via push endpoint.
FAQ
How long are messages retained?+
Default 7 days, configurable up to 31 days. Unconsumed messages past retention are discarded.
How do I ensure message ordering?+
Pub/Sub provides ordering keys (ordered within a key), or use Pub/Sub Lite (strict ordering within partitions, Kafka-like).
Technical details
- Auth type
- unknown
- Pricing
- unknown
- Protocols
- REST, gRPC
- SDKs
- python, javascript, typescript, go, java, csharp, php, ruby
- Response time
- 46 ms
- Last health check
- 5/12/2026, 7:37:36 AM
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