CMAK: Review, pricing, and best alternatives in 2026

Key takeaways

• CMAK (Cluster Manager for Apache Kafka) is a free, Apache 2.0-licensed tool originally built by Yahoo that provides multi-cluster management, partition reassignment, preferred-replica election, and optional JMX polling from a browser-based interface.
• The project is functionally stalled: the last stable release (3.0.0.6) was tagged on 29 April 2022, and multiple pull requests and feature requests have gone unanswered since.
• CMAK has a hard ZooKeeper dependency with no KRaft support. Apache Kafka 4.0, released on 18 March 2025, operates entirely without ZooKeeper, making CMAK incompatible with all clusters running that version.
• Security is limited to LDAP basic auth and coarse feature flags: there is no SAML/OIDC, no per-topic RBAC, and no audit log.
• For teams running KRaft clusters, needing message browsing, or requiring enterprise-grade access control, alternatives such as AKHQ, Kafdrop, Redpanda Console, or Kpow are worth evaluating.

What is CMAK?

CMAK (Cluster Manager for Apache Kafka), originally named Kafka Manager, is an open-source Kafka administration tool built at Yahoo and released under the Apache 2.0 licence. It provides a browser-based interface for managing one or more Kafka clusters from a single view.

The tool is built on Scala and the Play framework, and it requires a direct connection to a ZooKeeper ensemble to function. Its core feature set reflects the operational tasks Yahoo built it for: registering and monitoring clusters, creating and modifying topics, managing partitions, triggering preferred-replica elections, and polling JMX metrics from brokers.

CMAK is hosted at github.com/yahoo/CMAK. No commercial distribution, hosted offering, or paid support tier exists.

CMAK review

Functionalities

CMAK's feature set is narrowly focused on cluster operations. Its official README enumerates the following capabilities: KMClusterManagerFeature, KMTopicManagerFeature, KMPreferredReplicaElectionFeature, and KMReassignPartitionsFeature. In practice, this covers multi-cluster registration, topic creation and configuration, partition reassignment, preferred-replica election, and optional JMX metric polling at the broker and topic level.

Practitioner reviews describe these features as effective for their intended purpose. A 2022 Towards Data Science overview states: "For the most part, CMAK is primarily an Ops tool. It is also really good at partition reassignment." The same review notes that "multi-cluster management, dynamic topic configuration, partition creation, and replica change will cover most of your tasks." User webodmin, writing on GitHub Issue #776 in 2023, described CMAK as "very useful and convenient" — this from someone who had run it in production until a KRaft migration made it unusable.

What CMAK does not cover is equally significant. The tool has no message-browsing UI, no schema registry integration, no Kafka Connect management, and no ksqlDB or Flink support. These absences reflect a scope deliberately limited to administrative operations rather than data-plane visibility.

One limitation that affects day-to-day operations is CMAK's use of an internal caching layer rather than live data from broker APIs. Changes made to the cluster are not reflected in the UI immediately, because the interface polls for metadata on a fixed interval rather than subscribing to live state. This causes delays between an administrative action and its confirmation on-screen, which can mislead operators into believing a partition reassignment or offset reset has not taken effect. Tchiotludo, the author of AKHQ, cited this behaviour explicitly when describing why he built an alternative: "Kafka Manager have some kind of cache and you don't see your change on real-time. During develop, it was confusing to don't see your modifications" (r/apachekafka, 2019).

A related visibility gap appears during broker migrations. An operations specialist on r/devops noted that CMAK would report hours of catch-up replication completing in seconds, with no way to verify accuracy without querying the ZooKeeper shell directly: "CMAK would indicate hours of catch-up replication (by replicas) being completed in seconds whose correctness I could never figure out without going to the ZK shell" (Gathering opinions on Kafka management tools, 2021). For teams doing broker replacements or rebalances in production, this makes CMAK unreliable as a source of truth during the migration window.

One area where CMAK retains some value is as a learning tool. Its visual taxonomy of brokers, partitions, and replicas maps closely to Kafka's internal model, and some practitioners recommend it specifically for building familiarity with core concepts. A systems engineer on r/apachekafka wrote: "Spend some time to understand CMAK, it is really good, and the functions on the page can help you check the knowledge points or keywords you missed when reading the document" (Suggestions for learning Kafka, 2025). This applies to ZooKeeper-era clusters; the tool provides no equivalent value on KRaft deployments where it cannot connect at all.

The most consequential functional gap as of 2025-2026 is the absence of KRaft support. CMAK connects to Kafka through a ZooKeeper endpoint. GitHub Issue #776 has accumulated requests from named users since 2022, including akamensky, webodmin, ceeeekay, meethigher, and azhurbilo, all of whom confirm CMAK is unusable on ZK-less deployments. Maintainer patelh acknowledged the problem in 2022: "Yep, we'll phase it out but we'll need some place to store metadata. Either directly in Kafka or RDBMS. Still to be designed." As of May 2026, no implementation has shipped.

Practitioners hitting this wall in production confirm that the failure is hard and immediate. User dekanov on r/apachekafka wrote after standing up a test cluster: "I have just started my first Kraft test cluster. First problem is that it is not compatible with my Kafka Manager, which I can not get rid of entirely" (Running Kraft in production, 2023). The broader community has largely absorbed this as settled. Haarolean, a contributor to the Kafbat UI project, stated plainly on r/dataengineering: "CMAK is inactive for a couple years already" (Kafbat UI for Apache Kafka v1.0 is out, 2024).

Apache Kafka 4.0, released 18 March 2025, is the first major release to operate entirely without Apache ZooKeeper. CMAK is incompatible with any cluster running that version or later.

Deployment and operations

CMAK is distributed as source code requiring an sbt/Scala build. Docker images exist but are community-maintained (sheepkiller, TrivadisPF, intropro, hjben) rather than published by Yahoo. Kubernetes deployment is handled by the third-party eshepelyuk/cmak-operator Helm chart, not the upstream project.

Build friction is a recurring complaint. GitHub Issue #927 (December 2023, filed by zamek42) reports a compatibility problem on OpenJDK 17: "No JVMCI compiler found, but I use openjdk Java 17." Issue #922 (July 2023, filed by SimonMikolajek) flags build dependency problems on current sbt/Scala toolchains.

For larger clusters with JMX enabled, the README requires manual thread-pool tuning: cmak.broker-view-thread-pool-size=<3 * number_of_brokers> and a corresponding update-interval formula. There is no documented autoscaling path.

Operational reliability has also been questioned. A widely-cited issue (#550, originally filed in 2018 by mimani) describes long-running instances hanging after 20-30 days with RejectedExecutionException errors caused by thread-pool exhaustion. This pattern has not been addressed in any subsequent release.

The last binary release is 3.0.0.6, tagged 29 April 2022 by contributor mcjyang. No stable release has followed in the three years since.

Access control and security

CMAK supports LDAP basic authentication and a coarse feature-flag model. The feature flags can be enabled or disabled globally but provide no per-user, per-cluster, or per-topic granularity.

The README warns explicitly: "Warning, you need to have SSL configured with CMAK (pka Kafka Manager) to ensure your credentials aren't passed unencrypted... Note: LDAP is unencrypted and insecure." SSL must be configured manually; the default setup transmits credentials in plaintext.

There is no SAML or OIDC integration. GitHub Issue #933 (September 2024, naganaidu-rezi) asks: "how to configure custom SAML for Kafka Manager?" — a direct signal that SSO is wanted and absent. In practice, teams that require SSO and MFA have had to place CMAK behind a reverse proxy wired to an identity provider. A DevOps engineer on r/devops described their setup: "We use it with OKTA to enable SSO and MFA for Spark UI, Kafka Manager, Kibana and Kubernetes dashboard" (How do you handle apps that do not have built-in SSO support?, 2021). This approach works but adds operational overhead, requires a correctly configured proxy, and still does not provide per-topic or per-cluster access controls — it secures the front door without addressing what happens inside. Issue #926 (October 2023, xiaobao623) reports that enabling ZooKeeper ACLs breaks CMAK's connection entirely. Issue #932 (August 2024, qianghong000) covers TLS-to-ZK configuration complexity. There is no audit log.

For teams with compliance requirements, the access-control model is not enterprise-grade. It was designed for small, internally-trusted environments.

User interface

Practitioners describe the CMAK UI as functional and direct for operators already familiar with Kafka's internal model. The 2022 Towards Data Science overview calls it "a good and fairly straightforward UI" that handles Ops tasks without unnecessary friction for experienced users.

The consistent criticism is that the UI is dated by comparison to modern single-page-application tools. Redpanda's 2024 Kafka tools guide (vendor-authored, included here only for the descriptive claim it independently corroborates) describes it as "less intuitive and visually dated compared to newer tools... [lacking] advanced visualizations and interactive features." The absence of a message-browsing view is the most frequently cited specific gap: almost every practitioner comparison uses Kafdrop's topic-content screen as the counterexample.

There is no documented accessibility support.

Ecosystem

CMAK's ecosystem coverage is minimal. It connects to Kafka through ZooKeeper; it has no native integration with Schema Registry, Kafka Connect, ksqlDB, Flink, or any cloud-managed Kafka service.

The ZooKeeper dependency is particularly limiting for cloud deployments. Users on GitHub Issue #776 confirm that managed services — MSK, Confluent Cloud, Aiven, Redpanda Cloud — either lock down or no longer expose ZooKeeper endpoints, making CMAK incompatible with the majority of managed Kafka offerings. GitHub Issue #934 (October 2024, stefannmih) specifically flags compatibility problems with Confluent distributions.

The eshepelyuk/cmak-operator maintainer, the author of the most widely used Kubernetes deployment path for CMAK, recommends AKHQ as the better-maintained alternative: "AKHQ project seems to be the most active open source tool for managing and monitoring Kafka clusters. It could be missing some functionality from CMAK, but their developers are open for feature requests and contributions."

Customer support

CMAK has no commercial support offering. The only channel is GitHub Issues, and the maintainer response rate in 2023-2024 is low. Issues #925, #928, #929, #930, #931, and #933 all contain unanswered feature requests or release requests. A PR to add Kafka 3.3 compatibility (PR #924, submitted August 2023 by HenryCaiHaiying) remained unmerged as of the research date.

There is no documentation site, no community Slack or Discord, and no commercial-support option. The project has not been formally archived by Yahoo, but it has not received a stable release since April 2022.

Best for

CMAK suits small-to-medium teams running on-premises Kafka 2.x or ZooKeeper-era 3.x clusters, where the primary need is partition reassignment, preferred-replica election, and basic broker/topic visibility. It fits operators — SREs and platform engineers — who prefer a direct, Ops-oriented interface and have no compliance requirement for SSO, granular RBAC, or audit logging.

It is not a fit for any cluster running Kafka 3.3+ in KRaft mode, any Kafka 4.0 deployment, or any managed Kafka service where ZooKeeper is not user-accessible. It is also not appropriate for teams that need message inspection, schema management, Kafka Connect administration, or enterprise access controls.

CMAK pricing

CMAK is free and open-source software, released under the Apache 2.0 licence. There are no paid tiers, hosted offerings, or commercial distributions.

Pricing tiers

There is a single tier: free, self-hosted. You are responsible for all infrastructure, deployment, and operational costs.

Free trial

No trial is applicable. You can deploy CMAK directly from the GitHub repository or from a community-maintained Docker image.

CMAK competitors and alternatives

CMAK occupies a specific niche: free, ZooKeeper-era Kafka operations tooling. The wider ecosystem's move toward KRaft and richer feature sets has eroded that niche substantially. Most practitioners evaluating a new deployment now consider AKHQ, Kafdrop, Redpanda Console, or a commercial option before settling on CMAK.

For a broader comparison of Kafka management tools, see the Factor House Kafka tools guide.

What practitioners are moving to

Across r/apachekafka and r/devops, the migration path away from CMAK is well-trodden. AKHQ is the most frequently recommended direct replacement for teams that need live topic inspection alongside cluster administration — user thebrobotic on the CMAK replacement thread (2022) noted: "Started using this and I like it better than CMAK. Has more features like view data in a topic / live tail of a topic which is very nice." Kafbat UI (a maintained community fork of the original Provectus UI) has gained ground for teams running multi-cluster environments that also need OAuth 2.0 or Active Directory integration without a reverse-proxy workaround. For teams with compliance requirements or operating Kafka at significant scale, the gap between CMAK's feature set and commercial alternatives such as Kpow are substantial: per-topic RBAC, audit logging, and stateless deployment are not achievable in any configuration of CMAK.

Frequently asked questions about CMAK

How much does CMAK cost, and is there a free tier?

CMAK is free and open-source under the Apache 2.0 licence. There is no paid tier, hosted offering, or commercial support option. You self-host and bear all infrastructure costs.

When is CMAK a better choice than the alternatives?

CMAK suits operators managing on-premises Kafka 2.x or ZooKeeper-era 3.x clusters who need partition reassignment, preferred-replica election, and multi-cluster visibility, without budget for commercial tooling and without SSO or RBAC requirements.

When are the alternatives a better choice than CMAK?

If your cluster runs KRaft (Kafka 3.3+ or 4.0), uses a managed service, or requires message browsing, schema registry, SSO, per-topic RBAC, or an audit log, CMAK cannot meet those needs. AKHQ, Kafdrop, or a commercial option are better fits.

Is CMAK still actively maintained?

The last stable release is 3.0.0.6, dated 29 April 2022. Multiple PRs and feature requests have received no maintainer response since then. The project has not been formally archived, but it is not receiving new releases.

Does CMAK support Kafka 4.0?

No. Kafka 4.0 (released 18 March 2025) operates entirely without ZooKeeper. CMAK requires a ZooKeeper endpoint and has no KRaft support, so it is incompatible with Kafka 4.0 clusters.