Compatibility

klite aims for drop-in compatibility with standard Kafka clients. Any franz-go, librdkafka, or Java Kafka client should be able to connect, produce, consume, and use consumer groups without code changes beyond updating the broker address.

Protocol version

klite targets Kafka 4.0+ wire protocol compatibility (KIP-896 version floors). Only message format v2 (RecordBatch) is supported.

Client library compatibility

Client Library	Language	Status
franz-go	Go	Fully supported
confluent-kafka-go (librdkafka)	Go	Fully supported
librdkafka	C/C++	Fully supported
confluent-kafka-python	Python	Fully supported
kafka-python	Python	Fully supported
KafkaJS	Node.js	Fully supported
kafka-clients (Java)	Java	Fully supported
sarama	Go	Fully supported
Spring Kafka	Java	Fully supported

If your client speaks the standard Kafka wire protocol with message format v2, it should work with klite.

Supported APIs

klite implements 39 Kafka API keys across the core data path, consumer groups, transactions, admin, and authentication.

Core data path

API Key	API	Notes
0	Produce	Full support. acks=0, 1, all. LogAppendTime.
1	Fetch	Long-polling, size limits, KIP-74.
2	ListOffsets	Earliest, latest, timestamp lookup.
3	Metadata	Auto-create topics, topic IDs.
18	ApiVersions	Reports all supported APIs and version ranges.

Consumer groups

API Key	API	Notes
10	FindCoordinator	Group and transaction coordinators.
11	JoinGroup	Eager and cooperative rebalance.
14	SyncGroup	Partition assignment distribution.
12	Heartbeat	Session timeout enforcement.
13	LeaveGroup	Graceful consumer shutdown.
8	OffsetCommit	Per-group offset tracking.
9	OffsetFetch	Retrieve committed offsets.
47	OffsetDelete	Delete committed offsets.

Transactions & idempotency

API Key	API	Notes
22	InitProducerID	Producer ID assignment, epoch bumps.
24	AddPartitionsToTxn	Register partitions in a transaction.
25	AddOffsetsToTxn	Register group offsets in a transaction.
26	EndTxn	Commit or abort a transaction.
28	TxnOffsetCommit	Commit offsets within a transaction.
61	DescribeProducers	Inspect active producer state.
65	DescribeTransactions	Inspect active transactions.
66	ListTransactions	List all active transactions.

Admin APIs

API Key	API	Notes
19	CreateTopics	Name validation, config, partition count.
20	DeleteTopics	By name or topic ID.
37	CreatePartitions	Add partitions to existing topics.
32	DescribeConfigs	Topic and broker configs.
33	AlterConfigs	Set topic configs (legacy).
44	IncrementalAlterConfigs	Incremental config updates.
16	ListGroups	List all consumer groups.
15	DescribeGroups	Group membership and state.
42	DeleteGroups	Delete inactive consumer groups.
21	DeleteRecords	Advance log start offset.
60	DescribeCluster	Cluster metadata.
35	DescribeLogDirs	Log directory sizes.
23	OffsetForLeaderEpoch	Leader epoch offset lookup.

Authentication

API Key	API	Notes
17	SASLHandshake	SASL mechanism negotiation.
36	SASLAuthenticate	PLAIN, SCRAM-SHA-256, SCRAM-SHA-512.
51	AlterUserScramCredentials	Manage SCRAM users.
50	DescribeUserScramCredentials	List SCRAM users.

Explicitly unsupported

These Kafka features are intentionally not supported:

Feature	Reason
Multi-broker clustering	klite is a single-broker architecture. Durability comes from S3.
KRaft / ZooKeeper	No controller quorum needed.
Inter-broker APIs	LeaderAndIsr, StopReplica, UpdateMetadata, etc. are cluster-internal.
Kafka Connect	Server-side connector framework. Use standalone connectors.
Kafka Streams server-side	Kafka Streams clients work fine — they’re just producers and consumers.
Schema Registry	Not a broker feature. Use Confluent Schema Registry or Karapace alongside klite.
Share groups (KIP-932)	Not implemented.
Delegation tokens	Not implemented.
Message format v0/v1	Only v2 (RecordBatch) is supported. Very old clients may not work.
Quota enforcement	Configs are stored but not enforced.

Known differences from Apache Kafka

Behavior	Kafka	klite
Replication	ISR-based, configurable replication factor	None (single broker). S3 provides durability.
Partition reassignment	Dynamic across brokers	N/A (single broker)
Controller	KRaft or ZooKeeper	N/A (embedded, no election)
Log segments	Configurable segment size, roll on time/size	WAL segments, S3 flush is time-based
Tiered storage API	ListOffsets -4/-5	Not supported; S3 is transparent
Quotas	Enforced per client/user	Stored but not enforced

Testing your client

The quickest way to verify compatibility with your client:

# Start klite
./klite

# Run your application pointing to klite
export KAFKA_BOOTSTRAP_SERVERS=localhost:9092
# ... start your app

If you encounter a compatibility issue, check Troubleshooting or open an issue.

Next steps

• Quickstart — get started with your preferred client
• Supported APIs reference — version ranges and details
• Topic configs — supported per-topic configuration