# Ollama4j's Maven snippet ships a version placeholder, and its newest release is five months behind the branch

> A Java binding for the Ollama server's HTTP API, covering generation, chat, tools, tool-calling over MCP, embeddings, model management and, most recently, Prometheus export. The build and test tooling is the most carefully documented part of the project and also where the sharpest details sit: a private network address committed to the Makefile, formatting applied before every test run, and pre-commit hooks that update themselves on setup.

**ollama4j/ollama4j** — A simple Java library for interacting with Ollama server.

- Repository: https://github.com/ollama4j/ollama4j
- Website: https://ollama4j.github.io/ollama4j
- Stars: 508 · Forks: 85
- Language: Java
- License: MIT
- Published: 2026-09-10 · Updated: 2026-09-10 · Language: en
- Canonical page: https://hysenlabs.com/projects/ollama4j-ollama4j

## Both dependency snippets contain a template placeholder that never got filled in

The install instructions present two Maven paths and the dependency block is identical in both:

```xml
<dependency>
    <groupId>io.github.ollama4j</groupId>
    <artifactId>ollama4j</artifactId>
    <version>{{OLLAMA4J_VERSION}}</version> <!-- replace the version number here -->
</dependency>
```

The version value is a double-brace template placeholder, not a version. A comment acknowledges this and tells you to replace it.

That is the entire install path for Maven users, in both the central route and the packages route. It does not parse as XML version syntax that Maven will accept, so the first build after copy-paste fails on dependency resolution rather than on anything you did. The failure message points at the version, so it is diagnosable, but the snippet that a reader is told is ready to paste is not.

The double-brace form is the clue to what happened. It is a placeholder in a substitution syntax, which means the snippet came out of a generator or a template that expected to have the value injected before publishing and did not. So the two snippets were produced by the same process and both carry the same unfilled value, which means a reader has to determine the current version from the releases page and edit both.

The groupId is worth pausing on too, because it explains the dual publishing. The coordinate begins with a segment that follows the convention GitHub uses for its own package registry. That is what lets one coordinate resolve from either repository, and it is also why the two paths are documented as near-duplicates rather than as different artifacts.

## One coordinate across two repositories, and the token-free one is the better one

A note near the top of the usage section states that the project is now publishing artifacts to both a central repository and a GitHub package registry, with a link to the releases and an instruction to update the dependency version according to your own requirements.

So one group, one artifact name and one version resolve from two independent registries. Which one you get depends entirely on repository order in your build configuration, and nothing in the documentation states whether the two are byte-identical, how long both will be kept in sync, or which to prefer.

The practical difference is authentication, and it favours one path clearly. The central route needs no credentials at all. The GitHub packages route requires a server entry in your Maven settings file with a username and a password, where the password is a personal access token, and it requires adding a repository block to your build file or your settings. That is the conventional wiring and the identifiers in the two snippets line up correctly, but it means anyone using that route is putting a long-lived token into a file to fetch a library.

One detail in that repository block is off-pattern. It enables releases and snapshots. This project publishes numbered releases, and nothing in the documentation mentions a snapshot repository or a snapshot build. Leaving snapshots enabled on a dependency means a resolution will accept a snapshot if one is ever published, with a version that sorts ahead of the release you asked for. Disabling it costs nothing and removes that possibility.

The Gradle route is documented alongside both Maven ones, which is worth noting given what is in the repository: the project builds itself with Maven only. There is no Gradle build file at the root. So Gradle consumers are taking a Maven-produced artifact with no Gradle module metadata, which is fine for resolution but means none of Gradle's own dependency insight features apply to it.

## The newest release is a hundred and fifty-three days behind the branch

The release history is three entries, and the intervals between them are the story.

One point one point seven shipped 2026-04-28. One point one point six shipped 2025-12-04. One point one point five shipped 2025-11-18.

So sixteen days between the last two, then a hundred and forty-five days to the next. And the last push to the branch was 2026-09-28, which is a hundred and fifty-three days after the newest tag.

Read together, the cadence was roughly monthly through late 2025 and then stopped. A hundred and fifty-three days of commits sit on the branch with no release cut from them.

For a library that is version-pinned in a build file, that gap is the difference between what you can read in the source and what you can get from a registry. Anyone evaluating has two options and neither is documented: consume the released artifact and ignore five months of work, or build from the branch, which for a Maven project means the local install path rather than a dependency declaration.

The release names carry no body text, all three are just the version number. So the releases list tells you when and nothing about what changed, and the only record of what is in the unreleased 153 days is the commit history.

That said, the branch being active is real and worth stating: four days before the date this is being evaluated, there was a commit. The project is being worked on. It is being released less often than it is being worked on.

## Prometheus export is the newest capability, it is labelled beta, and its documentation is in another repository

The capability list runs to sixteen items, and the last one is marked as new. It is built-in metrics export for monitoring requests, model usage and performance in real time, and it carries two qualifications in the same line: that it is a beta feature where feedback is welcome, and that a separate examples repository holds the details.

So the most operationally significant thing in a client library is both the newest thing and the least documented in its own README.

The documentation being elsewhere is a pattern rather than an incident. The repository already points out to a separate website, and there is a documentation directory, and a Doxygen configuration file and a Makefile target that generates docs with Doxygen, and another target that generates them with the Maven javadoc plugin. That is three documentation outputs for one Java library, and the README's table of contents points to a fourth location.

The metrics capability also raises a question the README does not answer. Exporting metrics means a metrics registry in the process, and this is a library, so the registry would arrive in every consuming application rather than only in a service that opted in. Whether the exporter is enabled by default, whether it can be turned off, and what it costs when unused are not stated anywhere in the visible text. For a beta feature in a widely used client library, that is the first thing to check.

The other five capabilities worth singling out are all conditional on the server or the model rather than on the library: reasoning output where the model supports it, image input where the model supports vision, and the model management surface, which lists, pulls, creates and deletes models.

## Model deletion and basic auth are both library capabilities

Two entries in the capability list deserve a second look because they describe what a dependency can do, not what it can read.

Model management covers listing, pulling, creating, deleting and getting details. Deleting a model is a destructive operation against the server, and this library exposes it. A consumer that depends on Ollama4j to generate text is holding, through its dependency graph, a code path that can remove models from whatever server it is pointed at.

That is not a criticism of the API surface. A complete binding should expose the full server API, and a library that omits delete would be the surprising one. It is a reminder that the blast radius of a dependency is the union of what the server will accept from anyone holding its credentials.

Authentication supports both basic auth and bearer tokens. Two forms is generous, and Ollama supports both.

Which brings up the requirements section, which is one link to the Ollama project homepage and nothing else. No statement about whether the server should be bound to loopback, no note that a default Ollama install has no authentication at all, no guidance on what to do when the server is reachable from a network. For a library whose capability list includes bearer tokens and basic auth, and whose model-management entry includes deletion, that is the gap worth noting: the authentication features exist for deployments that have configured authentication, and the documentation never says the default is unconfigured.

The same gap shows up in the integration test targets. The minimal local subset runs a single test class, and it is the authentication one. So of everything the library can do, the one path exercised by the smallest integration run is the one where the server is configured.

Timeouts are a first-class capability covering connect, read and write separately, which is the right granularity for a streaming API, and a related search term suggests users go looking for exactly this.

## Every test target reformats your source before it runs

The Makefile has a small number of targets and one of them is a prerequisite on nearly all of them.

There is a target that checks formatting by invoking the Maven formatting plugin in check mode, and one that applies formatting by invoking the same plugin in apply mode.

The apply target is then a dependency of the build, of the full build, of the unit tests, and of all three integration test targets.

So running the tests modifies your working tree. A developer with an uncommitted change on the line they were editing gets their files rewritten by a formatting tool before any test executes, and the diff they then look at is a mix of their work and a formatter's.

This is the usual consequence of wiring a mutating step into a read-only command, and it is a real ergonomic cost rather than a bug. It also interacts badly with a project that has a pre-commit setup, because now there are two things that can rewrite your files: the hooks and the test target.

The same prefix appears on the build target, so a build formats before compiling as well.

There are two build paths and they differ in a way that is only visible here. The ordinary build skips GPG signing and skips javadoc generation, both on the command line. The full build does neither skip. So the local build is not the release build, and the difference is three flags in a Makefile rather than a sentence anywhere in the documentation.

Formatting itself is handled by a Maven plugin with a check mode and an apply mode, and the hooks come from a pre-commit configuration file at the repository root.

## A private network address is committed in the remote integration target

One Makefile target sets an Ollama host to a private address.

The target exports a flag telling the tests to use an external server rather than starting their own, then exports the host as a literal address on port 11434, then runs the integration profile. The same target also skips GPG signing, which the ordinary build also does.

That address is a private network address, and it is in a public repository. It is almost certainly a developer's own machine on their own network, which means it tells anyone reading it something about their network layout and it means the target cannot work for anyone else.

The other two integration targets are better behaved. The local ones export the external-host flag as false, so the tests start their own Ollama, which is why the setup target refuses to continue unless Docker is present. The remote one flips the same flag to true.

So there are three integration modes and one of them is hardcoded to a machine that is not yours. The obvious fix is to read the host from an environment variable, which is what the flag already suggests is possible, but the committed literal takes precedence over whatever a user exports.

This is the kind of detail that is genuinely useful to know before you run the build, and it is the sort of thing that gets left in a Makefile for years because nobody is hurt by it except the person who eventually tries the target.

## The setup target updates every pre-commit hook, and an IDE directory is in the repository

The default target runs the development setup, and the setup does four things in order.

It checks that the pre-commit tool is installed and exits if not. It checks that Docker is installed and exits if not. It installs the git hooks. It then runs the pre-commit autoupdate command. And finally it reinstalls the hooks so the updated versions take effect.

The autoupdate step is the interesting one. It contacts the upstream repository of every hook in the configuration file and moves each one to its newest version. So the documented way to set up a development environment silently changes which third-party code will run in your commits, at whatever revision those projects happen to be at today.

That is a deliberate choice rather than an accident, and it is a common one in the Python and JavaScript hook ecosystems. It is also the single most consequential line in a Makefile that has no other surprises, because it is the difference between your hooks being pinned and your hooks being current. Anyone who needs a pinned toolchain has to run the install hook step without the autoupdate step, and nothing says so.

Two smaller repository-hygiene observations round this out.

An IDE project directory is committed at the root. That directory normally carries per-developer run configurations and workspace state, and it is conventionally excluded from version control.

And the README carries twelve commented-out badge lines. They cover repository size, top language, three separate download counters from a build service, a total downloads figure, a hit counter pointed at a third-party service, and a language count. All twelve are disabled using a comment syntax, so nothing renders. What remains visible in the badge area is a continuous-integration workflow badge and a coverage service badge.

The repository is otherwise conventionally laid out: a Maven build file, a source directory, a documentation directory, a security policy, a contribution guide, a code of conduct, a licence, and a citation file. The citation file is the one that stands out, since it marks the project as a citable research artifact rather than only a wrapper library.

## Conclusion

Use Ollama4j if you are calling Ollama from a JVM and want the whole API surface in one typed library rather than hand-rolling HTTP calls, since the options builder and timeout controls are the real value. Do not treat the capability list as sixteen guarantees, because two of them depend on the model rather than the library, and model deletion is among them. Verify first which version resolves, since the copy-paste dependency snippet does not compile as printed and the newest release predates the branch by five months.

## FAQ

### What can Ollama4j do?

The library lists sixteen capabilities covering text generation, multi-turn chat, tool and function calling, tool calling over the Model Context Protocol, reasoning output, image input, embeddings, asynchronous generation, custom chat roles, model management including deletion, server connectivity utilities, authentication, an options builder, timeouts, logging, and Prometheus metrics export. Two of the sixteen depend on the model's capabilities rather than on the library.

### How do I add Ollama4j to a Maven project?

Add a dependency with the group id io.github.ollama4j, the artifact id ollama4j, and a version. The snippet in the documentation leaves the version as an unfilled double-brace placeholder that you must replace with a number from the releases page. The same coordinate resolves from either a central repository or a GitHub package registry, and the latter additionally requires a personal access token in your Maven settings.

### Does Ollama4j support authentication to the Ollama server?

Yes, it lists both basic auth and bearer token support as capabilities. The requirements section, however, contains only a link to the Ollama project homepage and says nothing about configuring authentication on the server or about binding the server to loopback, which matters because the library also exposes model deletion.

### Is Ollama4j's metrics export stable?

No. Prometheus metrics export is labelled a new beta feature where contributions are welcome, and its documentation lives in a separate examples repository rather than in this project's README. The README does not say whether the exporter is enabled by default or how to turn it off, which is worth checking since it would add a metrics registry to any application depending on the library.

### How do I run Ollama4j's tests?

Through Makefile targets that wrap Maven profiles. The unit test target runs one profile and the three integration targets run another, with a flag choosing between a locally started server and an external one. Every one of those targets depends on a formatting step that rewrites your source first, and the remote integration target hardcodes a private network address as the external host.

## Sources

- [License: MIT](https://github.com/ollama4j/ollama4j/blob/main/LICENSE)
- [ollama4j/ollama4j on GitHub](https://github.com/ollama4j/ollama4j)
- [Project website](https://ollama4j.github.io/ollama4j)
- [README](https://github.com/ollama4j/ollama4j/blob/main/README.md)
- [Releases](https://github.com/ollama4j/ollama4j/releases)

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Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/ollama4j-ollama4j