Best Kafka UI tools for Karapace Schema Registry

Tools compared

Rank	Tool	Total (out of 100)	Out of the data path	Production access on request	Audit trail per person	Directory and Kafka sign-in	Multiple registries	Karapace depth	Cost a year, one cluster (modelled)
1	Kpow	91	One container, no external database, not a proxy	Temporary policies, staged approvals, masking	Every action and data read, by user	SAML, OpenID, LDAP	Several registries of any kind per cluster (Enterprise)	Aiven and Instaclustr guides; Karapace fix in 95.1	$7,380
2	Kafbat UI	64	One container	Read-only clusters, no approvals	Opt-in log, no view in the product	OAuth2, OIDC, LDAP	One per cluster	Forked-from project in Instaclustr guide; basic, OAuth, mTLS	$8,640
3	AKHQ	58	One container	Group roles, no approvals	Opt-in topic, no reads	LDAP, OIDC	One per cluster	Instaclustr guide; basic auth; Avro references	$8,640
4	Lenses	50	HQ on PostgreSQL plus an agent per cluster	Global masking, no approvals	In-product audit log	SSO from Team tier	One per environment	Compatible registries; Karapace not documented	$6,880 for 15 users; custom above
5	Redpanda Console	46	One container	None in the free build; RBAC licensed	No record on non-Redpanda brokers	OIDC (Enterprise)	One per deployment	Basic, bearer, client TLS; Karapace not named	$8,640 plus an unpublished licence for sign-in and RBAC
6	Conduktor	54	Console on PostgreSQL; Gateway, a proxy, for data-level controls	Masking exemptions, owner approval	70+ event types in the UI	LDAP, OIDC	One per cluster	Compatible registries; compatibility check and compare	$32,880; $122,880 with Gateway Core and Protect

The tools, ranked for teams using Karapace

What teams using Karapace need

This page is about tools for a team that already runs Karapace, Aiven’s open-source registry, whether as part of Aiven for Apache Kafka, as the Schema Registry add-on on NetApp Instaclustr, or self-managed, and wants one UI for reading topics, managing subjects and governing who does what. It does not rank the registries themselves; Karapace, Confluent’s registry, Apicurio, AWS Glue and Redpanda’s are compared in the best tools for Kafka schema registry management. The services Karapace usually arrives with have their own pages: the best Kafka tools for Aiven for Apache Kafka and the best Kafka tools for NetApp Instaclustr managed Kafka. Aiven’s own console shows Karapace schemas in a tab on each topic, and is scored on the Aiven page rather than here, because it reaches only Aiven’s registry.

Out of the data path. Karapace is two services under one name. The Karapace README describes it as an implementation of both Schema Registry and Kafka REST, and Aiven’s Karapace documentation says each can be enabled or disabled independently, with the registry’s APIs separate from the REST Proxy’s. The registry sits beside the brokers: clients fetch schemas and serialise records themselves. The REST proxy is different, because applications that produce and consume over HTTP send their records through it. A management tool needs the registry API only, and reaches the brokers as an ordinary Kafka client, so it adds nothing to either path. Kpow is one container with no external database, installed in your own environment and out of the data path, and Karapace itself keeps no database either: it stores its state in a Kafka topic. Conduktor Console also connects directly, with a PostgreSQL database of its own; Conduktor’s data-level controls, such as encryption, masking of the data itself and virtual clusters, run in Conduktor Gateway, a Kafka proxy that client applications connect through.

Production access on request. Karapace’s own access control is coarse by design. Its authorisation file, set with registry_authfile and described in the Karapace README, grants a user Read or Write on a regular expression of resources, and Write includes all mutable operations, deleting schema versions among them. Registering a new version and deleting an old one are therefore one permission at the registry. In a tool shared by a platform team, the distinction has to come from the tool: Kpow’s authorization overview lists SCHEMA_CREATE, SCHEMA_EDIT_VERSION and SCHEMA_DELETE as separate actions, and staged mutations hold a deletion until a second person approves it. Where production access is needed for one task, Kpow’s temporary policies grant it for a set time and then expire. These controls are compared across the field in the best tools for Kafka role-based access control (RBAC).

Karapace also keeps the registry’s state somewhere a Kafka tool can reach. Karapace’s import mode documentation explains that a mode is not held in a separate store: setting one appends a record to the internal _schemas topic, alongside the schema and config records. Produce rights on that topic are, in effect, registry rights, so a tool that lets people write to any topic they can see has handed out the registry too. Kpow’s TOPIC_PRODUCE is an action of its own in the same authorization model, so a team can read the schemas topic while nobody but the registry writes to it.

Audit trail per person. The registry changes that matter most on Karapace are few and easy to miss afterwards: a compatibility mode changed, a version deleted, a subject removed, or a subject switched to IMPORT mode. The import mode documentation states that IMPORT skips compatibility checks entirely and lets the client choose schema IDs, which is right for a migration and wrong for a production subject left in that mode. Karapace can refuse every mode change with mode_mutability set to false, read at start-up, but where mode changes stay allowed, the record of who made them has to come from the tool. On a managed service the tool often connects with one registry user, so the registry’s own view names that user rather than the engineer; Kpow’s audit log names the person from the identity provider. The options are compared in the best tools for Kafka audit logging.

Directory and Kafka sign-in. The tool has to sign people in through the company directory and connect to the brokers and the registry with whatever each requires. On Aiven and on the Instaclustr add-on, Karapace is reached with HTTP basic authentication, and Kpow’s guides use exactly that. Current Karapace releases can also validate OIDC bearer tokens against an identity provider, according to the README; a team that has turned that on should test its tool against it, because Kpow’s documented Karapace setups use basic authentication.

Multiple registries. Karapace often arrives as the second registry. Karapace’s import mode exists so that schemas can move from another registry with their original IDs and version numbers, because, as its documentation puts it, data already on your topics refers to schemas by ID, and a migration that reassigned IDs would leave that data unreadable. Until every producer has moved, the old registry and Karapace both serve the same cluster. A tool that attaches one registry per cluster shows only one of them beside the topics they serve.

Karapace depth. The Karapace README states that Karapace is compatible with Confluent Schema Registry 6.1.1 at the API level, with caveats on schema normalisation and error messages, and that it aims to support new Schema Registry versions in a reasonable time. A tool built against Confluent’s registry therefore needs testing against Karapace, not just a URL. Kpow’s release 95.1 records one such case: a regression in Kpow’s new schema observation engine that affected Karapace users, found and fixed. Aiven’s documentation also shows where a managed Karapace differs: schema references are supported for Avro and Protobuf, and not for JSON Schema.

No tool here leads on every point: Lenses has the stronger query model with SQL over topics, and Conduktor’s masking can exempt named users or groups, which no other tool here does. Kpow governs people working through Kpow, so applications keep their own Karapace credentials and Karapace’s own authorisation file stays the control for them.

Kpow and Karapace in public

No Factor House customer has yet described in public how it runs Kpow with Karapace, so this section names none. The public record is the documentation and Factor House’s own material. Aiven’s own documentation carries a Use Kpow with Aiven for Apache Kafka guide that describes Kpow as monitoring, managing and exploring Aiven’s brokers, its Karapace Schema Registry and its standalone Kafka Connect service. The Kpow features page lists Aiven Karapace among Kpow’s compatible services, and Kpow’s Aiven and Instaclustr guides give the Karapace settings for each. Factor House’s guide to integrating Confluent-compatible schema registries with Kpow runs Karapace beside Confluent Schema Registry and Apicurio on one Kafka cluster, and its London workshop material on GitHub runs Kpow against an Instaclustr cluster with the Karapace add-on. Factor House and NetApp Instaclustr also presented Migrating to open source Kafka together. The wider picture for each service is on the Aiven page and the Instaclustr page.

How a team runs Kpow with Karapace

Installing it beside the cluster. Kpow runs as one Docker container, a Java JAR or through the Helm charts, in a network that can reach the brokers and Karapace. It needs no external database, because its snapshots, metrics and audit log live in topics on the cluster itself.

Connecting to Karapace on Aiven. Aiven’s managed Karapace uses basic authentication, and the Aiven guide sets SCHEMA_REGISTRY_NAME, SCHEMA_REGISTRY_URL, SCHEMA_REGISTRY_AUTH=USER_INFO, SCHEMA_REGISTRY_USER and SCHEMA_REGISTRY_PASSWORD from the service’s connection details. The same Kpow instance manages the brokers and Aiven’s standalone Kafka Connect service.

Connecting to Karapace on Instaclustr. The Instaclustr guide uses the same settings for the Karapace add-on, with the registry URL that carries a CA-signed certificate, on port 8085. The firewall is the step teams miss. Factor House’s workshop material records that linking Kafka Connect to an Instaclustr Kafka cluster updates the brokers’ firewall rules but not Karapace’s, so the Kpow host and the Connect nodes have to be added to the Karapace allow list by hand.

Holding several registries. SCHEMA_REGISTRY_RESOURCE_IDS lists more than one registry for one Kafka cluster, each configured with its own prefix, such as KARAPACE_SCHEMA_REGISTRY_URL beside CONFLUENT_SCHEMA_REGISTRY_URL, and the list order sets the order in the UI (schema registry configuration). During a migration into Karapace the old registry and the new one sit side by side under the same roles and audit log; more than one registry needs Kpow Enterprise.

Reading the registry efficiently. By default Kpow reads every schema with its metadata in one REST call; setting SCHEMA_REGISTRY_OBSERVATION_VERSION=1 switches to the older per-subject reads, which cost two calls per schema and give compatibility at the aggregate level (schema registry configuration). The Karapace regression fixed in release 95.1 was in the newer engine, and the per-subject setting remains available for any registry where the bulk read does not fit.

Managing subjects. The schema view creates Avro, JSON Schema and Protobuf subjects, edits versions, updates a subject’s compatibility and deletes subjects, and the Kpow features page lists a visual version diff. RBAC sets Allow, Deny or Stage per action, so a team can create versions in its own subjects while a deletion waits for approval.

Reading records. Data inspect decodes Avro, JSON Schema and Protobuf records with the registry’s SerDes, and data policies mask sensitive fields in inspect results on the server. The same view reads the registry’s storage topic itself, _schemas by default and _karapace in the multi-registry guide’s setup, which is a quick way to see what Karapace has recorded without write access to it.

Signing people in and keeping the record. Engineers sign in through SAML, OpenID Connect or LDAP, tenants give each team its own view of a shared cluster, and the audit log records each action, schema changes and data inspect queries included, with a webhook that sends the records to Slack, Microsoft Teams or any HTTP endpoint, such as a SIEM collector.

Kpow live demo

See the Kpow schema view

The live Kpow demo runs on Apache Kafka clusters on Amazon MSK, and the registry attached to it is AWS Glue rather than Karapace. Open Schema to see the view a team gets on a Karapace registry too: each subject with its version, compatibility mode and status, with no signup.

For platform teams choosing a Kafka tool for Karapace.

Try the Kpow demo→

FAQ

What is the best Kafka UI for Karapace?

On this page’s rubric, Kpow, with 91 of 100 points: its documentation covers Karapace on Aiven and on Instaclustr, it separates creating, editing and deleting schemas under per-person roles and approvals, holds Karapace beside other registries on one cluster, and runs as one container with no external database. Kafbat UI is the highest-scoring free option.

Does Kpow support Karapace?

Yes. Kpow’s schema registry documentation names Karapace among the Confluent-compatible registries it supports, its Aiven and Instaclustr guides give the settings, and the Kpow features page lists Aiven Karapace among its compatible services.

Does Karapace have its own UI?

No. The Karapace README describes a registry and a REST proxy with HTTP APIs, and the schema registry tools page notes that the management layer has to come from somewhere else. On Aiven, the Aiven console shows a topic’s schemas; elsewhere a Kafka UI fills that role.

Can one Kafka UI manage Karapace and another registry together?

Kpow attaches more than one registry to a single Kafka cluster with SCHEMA_REGISTRY_RESOURCE_IDS, of the same or different kinds, in Kpow Enterprise. The other UIs on this page attach one registry to each cluster connection.

Does a Kafka UI need Karapace’s REST proxy?

No. A management tool needs the registry API to manage schemas and connects to the brokers as an ordinary Kafka client. The REST proxy serves applications that produce and consume over HTTP, and Aiven lets each service be enabled on its own.

Is there a free Kafka UI for Karapace?

Kpow Community Edition is free on up to 3 clusters and 10 users. Kafbat UI and AKHQ are open source. Several registries per cluster, RBAC, masking, staged approvals and the audit log need Kpow Enterprise. More free options are compared in the best free Kafka UI tools in 2026.

How these tools were scored

Four of the six criteria are the ones Factor House scores on every page for teams that share a Kafka cluster; the other two are holding several registries and the depth of documented Karapace support. They are listed here in order of weight. Each criterion is scored 0 to 10: 10 where a tool is the only one here doing it or clearly the best, 8 for a clean documented pass, 5 or 6 for partial support or support that needs work the reader must verify, 1 to 4 for a weak or indirect form, and 0 where it is absent.

1. Out of the data path (counts three times). The tool should run in your own environment, reach the brokers and the registry over the same private network your applications use as an ordinary client, and keep no data outside your own cluster. Scored lower: tools that need an external database of their own, and tools whose controls work only when application traffic passes through a vendor’s proxy. A self-hosted container with no external database and no proxy scores 9, a tool with a database of its own 6, one with several databases or an agent per cluster 4, and one that needs both a database and a proxy for its controls 3; 10 is kept for an option with nothing to deploy at all, and none is scored here. This criterion is scored the same way on every Factor House page that uses it, and only its weight changes with the reader.

2. Production access on request (counts twice). Whether an engineer can be granted access to production for one task and have it expire, whether a destructive change, such as a subject deletion or a compatibility change, can be held for a second person’s approval, and whether sensitive fields can be masked from people who do not need them.

3. Audit trail per person (counts twice). Whether the tool records each action, reads included, against the person from the identity provider, and whether that record can be read in the product and sent to the systems that keep it long term.

4. Directory and Kafka sign-in (counts once). Whether people sign in through SAML, OpenID Connect or LDAP, and whether the tool connects to the brokers with the same SASL or TLS settings as any Kafka client.

5. Multiple registries (counts once). Whether one Kafka cluster can have more than one registry attached, of the same or different kinds, and whether one deployment reaches several clusters. These scores are the same as on the best tools for Kafka schema registry management and the best Kafka UI tools for Confluent Schema Registry for the tools scored there.

6. Karapace depth (counts once). Whether the tool’s own documentation, or Aiven’s or Instaclustr’s, gives a Karapace setup with it, whether it connects with the authentication Karapace uses, and whether it handles schema references, version comparison and compatibility edits. A tool that connects to Confluent-compatible registries in general but has no Karapace setup documented anywhere scores 5.

Costs are modelled for one production cluster and 25 engineers at $120 per engineer hour, using the same hours per tool class as Factor House’s other comparison pages. Tools with a licence carry the published price plus 2 hours a month to run. The open-source UIs carry 6 hours a month, $8,640 a year, to run, secure and keep current. Kpow’s $7,380 uses the published price of $4,500 per cluster with 100 users included. Lenses publishes a Team price of $4,000 a year for up to 15 users on one cluster, so 25 engineers is a custom quote. Conduktor’s Console is $1,200 a seat on AWS Marketplace, and its Gateway Core and Gateway Protect prices are added for the data-level controls; Conduktor prices Gateway per cluster with a 3-cluster minimum, and the listing does not say how many clusters that figure covers. Kpow Community Edition is free for 3 clusters and 10 users, so a 25-engineer team is on Enterprise. The cost of Karapace itself is not counted, as every option here uses the same registry. For free options compared at any team size, see the best free Kafka UI tools in 2026.

The criteria map onto Karapace’s features in the figure below.

F1 From Karapace feature to what a Kafka tool has to do

What Karapace does What the tool has to do

Two services A Confluent-compatible schema registry and a Kafka REST proxy, enabled independently on Aiven Use the registry API only, and reach the brokers as an ordinary Kafka client rather than through the REST proxy

Storage Schemas, compatibility settings, modes and subject deletions are records in a Kafka topic, _schemas by default Treat produce rights on that topic as registry rights, and let people read it without being able to write to it

Access control An authorisation file grants Read or Write per subject pattern, and Write includes deleting schema versions Separate creating, editing and deleting per person, and hold deletions for approval

Modes IMPORT mode skips compatibility checks so schemas keep their IDs during a migration Hold several registries side by side while a migration runs, and record who changed what

Compatibility Confluent-style compatibility per subject or globally, with BACKWARD as the default Show each subject's mode, compare versions, and let only permitted people change the mode

Security HTTP basic authentication from the authorisation file, or OIDC bearer tokens in current releases Connect with the credential the managed service issues, usually basic authentication on Aiven and Instaclustr

API level Compatible with Confluent Schema Registry 6.1.1 at the API level, with caveats on normalisation and error messages Be tested against Karapace releases, and fall back to per-subject reads where a bulk call does not fit

Every option is scored from 0 to 10 on each criterion, from the evidence and sources this page cites, and the reason for each score is on its card. The criteria are weighted: Out of the data path counts three times, Production access on request counts twice, Audit trail per person counts twice, Directory and Kafka sign-in counts once, Multiple registries counts once and Karapace depth counts once, for a total out of 100. Out of the data path counts three times. Karapace is built so that producers and consumers fetch schemas and check records in their own client libraries, and it keeps its own state in a Kafka topic rather than a database, so a tool that applications connect through, or that needs a database of its own, adds the component that design leaves out. Production access on request and the per-person audit trail count twice, because Karapace's own access control grants Write or Read per subject pattern, and a Write that deletes a schema version or switches a subject to IMPORT mode reaches every producer and consumer of that subject. Directory sign-in, holding several registries, and the depth of documented Karapace support count once. This page is published by Factor House, which makes Kpow. Every option is scored on the same rubric and the same sources: Kpow's per-criterion scores are set the same way as every other option's and are not adjusted, and the weights apply to every option alike. Kpow ranks first on its total of 91 out of 100. The other options follow by total. Conduktor is listed last whatever its total; on its total of 54 it would place fourth.

Related reading

• Kafka: the complete guide
• Best tools for Kafka schema registry management
• Best Kafka tools for Aiven for Apache Kafka
• Best Kafka tools for NetApp Instaclustr managed Kafka
• Best Kafka UI tools for Confluent Schema Registry
• Best Kafka UI tools for AWS Glue Schema Registry
• Integrate Confluent-compatible schema registries with Kpow
• Best Kafka governance tools for financial services