Freedom251 › Schema Registry Software
Karapace
What Karapace is
Karapace is Aiven-built, open-source Schema Registry and REST Proxy software for Aiven for Apache Kafka. Its registry stores and versions schemas and can check compatibility before a change is published. It accepts Avro, Protobuf, and JSON Schema; schema references are supported for Avro and Protobuf. The REST Proxy provides HTTP APIs for producing and consuming Kafka events, making it usable from scripts, curl, and HTTP-based services. OAuth 2.0/OIDC authentication is supported for both the registry and proxy. Registry access can use access control lists, while OIDC role-based authorization can restrict operations by HTTP method. The project documents Docker setup and installation from source with pip, and states API-level compatibility with Schema Registry 6.1.1. Aiven's Kafka free tier includes the registry and proxy and is intended for learning, prototyping, and evaluation. Its Free plan costs nothing, with throughput up to 250 KiB/s, retention up to three days, and up to five topics with two partitions each. The Developer plan is $35 a month. Built-in schema backup was removed in version 6.0.0 and is no longer maintained in the project.
Who it suits
It suits Kafka users who need schema storage and compatibility checks, or HTTP access to produce and consume events. The included free tier is described for learning, prototyping, and evaluation.
What it does well
- Open-source software with a free tier.
- Supports Avro, Protobuf, and JSON Schema.
- REST Proxy provides HTTP event APIs.
- Supports OAuth 2.0/OIDC authentication.
- Documents Docker setup and pip installation.
What to know first
- Built-in schema backup was removed in version 6.0.0.
- Free tier retention is up to three days.
- Free tier supports up to five topics.
Limits
The Free plan costs nothing and includes up to 250 KiB/s throughput, retention up to 3 days, and up to 5 topics with two partitions each. The Developer plan costs $35 a month and includes up to 1 MB/s throughput, retention up to 3 days, and up to 20 topics with a maximum of 100 partitions.
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Free | $0/month · Up to 250 KiB/s throughput · retention up to 3 days · up to 5 topics, each with two partitions · Schema Registry and REST proxy included | Free |
| Developer | $35/month; $0.04/hour · Up to 1 MB/s throughput · retention up to 3 days · up to 20 topics (max 100 partitions) · Schema Registry and REST proxy included | $35 a month |
As aiven.io lists them, read 2 Oct 2026. The maker's own page has the final word.
Getting started
- Open the Aiven Karapace documentation website
- Choose Aiven’s Kafka Free plan or Developer plan
- Deploy using the documented Docker setup or install from source with pip
- Configure the Schema Registry and REST Proxy for your Kafka use
- Set up authentication and, if needed, registry authorization
Verdict
Karapace combines schema management with an HTTP proxy for Kafka events, with authentication and authorization options. Note that built-in schema backup is no longer maintained, and the free-tier capacity has defined throughput, retention, and topic limits.
Questions
Is Karapace open source?
Yes. Karapace is described as open source.
What does the Free plan cost?
The Free plan costs nothing, billed at $0/month.
What does the Free plan include?
It includes up to 250 KiB/s throughput, retention up to 3 days, up to 5 topics with two partitions each, and the Schema Registry and REST Proxy.
What formats does Karapace support?
It supports Avro, Protobuf, and JSON Schema registration. Schema references are supported for Avro and Protobuf.
How can Karapace be deployed?
The project documents Docker-based setup and installation from source with pip.
What is the Developer plan price?
The Developer plan is $35 a month, billed at $35/month; the listed hourly price is $0.04/hour.
Facts from Karapace's own pages
- Authentication
- Karapace supports OAuth 2.0/OIDC authentication for Schema Registry and the REST Proxy. · aiven.io, 2 Oct 2026
- Authorization
- Schema Registry authorization uses access control lists, and OIDC role-based authorization can restrict operations by HTTP method. · aiven.io, 2 Oct 2026
- Company headquarters
- Aiven says it is headquartered in Helsinki, Finland. · aiven.io, 2 Oct 2026
- Compatibility
- The project states that Karapace is compatible with Schema Registry 6.1.1 at the API level and supports all operations in that API. · github.com, 2 Oct 2026
- Deployment
- The project documents Docker-based setup and installation from source with pip. · github.com, 2 Oct 2026
- Founded
- 2016 · aiven.io, 28 Sept 2026
- Free tier scope
- Aiven’s Kafka free tier includes Karapace Schema Registry and is described as intended for learning, prototyping, and evaluation. · aiven.io, 2 Oct 2026
- Headquarters
- Helsinki, Finland · aiven.io, 28 Sept 2026
- HTTP access
- The REST Proxy exposes APIs for producing and consuming Kafka events over HTTP, including use from scripts, curl, and HTTP-based services. · aiven.io, 2 Oct 2026
- Identity providers
- The OAuth/OIDC setup documentation lists Auth0, Okta, Google Identity Platform, and Azure as example compliant providers. · aiven.io, 2 Oct 2026
- Integrations
- The Aiven Terraform Provider supports managing Karapace Schema Registry authorization ACL entries. · aiven.io, 2 Oct 2026
- Notable limit
- Karapace’s built-in schema backup functionality was removed in version 6.0.0 and is no longer maintained in the project. · github.com, 2 Oct 2026
- Schema management
- The Schema Registry stores and versions schemas and can check compatibility before changes are published. · aiven.io, 2 Oct 2026
- Supported formats
- Karapace supports Avro, Protobuf, and JSON Schema registration; schema references are supported for Avro and Protobuf. · aiven.io, 2 Oct 2026
- What it does
- Karapace is an Aiven-built open-source Schema Registry and REST Proxy for Aiven for Apache Kafka. · aiven.io, 2 Oct 2026
Where Karapace stands on Freedom251
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