jackson-module-kotlin VS spring-fu

Compare jackson-module-kotlin vs spring-fu and see what are their differences.


Module that adds support for serialization/deserialization of Kotlin (http://kotlinlang.org) classes and data classes. (by FasterXML)


Configuration DSLs for Spring Boot (by spring-projects-experimental)
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jackson-module-kotlin spring-fu
9 12
1,059 1,654
0.5% 0.4%
9.1 0.0
1 day ago about 2 months ago
Kotlin Java
Apache License 2.0 Apache License 2.0
The number of mentions indicates the total number of mentions that we've tracked plus the number of user suggested alternatives.
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.


Posts with mentions or reviews of jackson-module-kotlin. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2022-10-19.
  • Jackson, moshi or kotlinx.serialization?
    8 projects | /r/Kotlin | 19 Oct 2022
    Jackson's learning curve is a lot lower (it helps that it's older and more popular, so there's more guides online), and it has a lot more options. However, Jackson doesn't fully support Kotlin, for example: value classes. For this reason, I would avoid it.
    8 projects | /r/Kotlin | 19 Oct 2022
    strictNullCheck option in the Kotlin module doesn't cover non-object-field situations at all. https://github.com/FasterXML/jackson-module-kotlin/issues/479
  • From Java to Kotlin. There and back again
    7 projects | dev.to | 1 Apr 2022
    You should add Jackson Module Kotlin in your project. After that, you can't specify a type of object explicitly.
  • How Cloudflare security responded to log4j2 vulnerability
    3 projects | /r/programming | 11 Dec 2021
    Not really, you just need to handle some standard types and have a good extension mechanism to let the user implement factories. That library having built in support for UUID and datetime is probably a bit much, I'd prefer a plugin like https://github.com/FasterXML/jackson-module-kotlin
  • Ktor vs Spring for creating an API
    2 projects | /r/Kotlin | 2 Sep 2021
    There is a bug at this very moment that makes it literally impossible to deserialize [1, 2, 3, null] into a List with Jackson's Kotlin module. Yes- even if you set KotlinModule(strictNullChecks = true). It's just broken. (Here's the link: https://github.com/FasterXML/jackson-module-kotlin/issues/479)
  • Kotlin Team AMA #3: Ask Us Anything
    52 projects | /r/Kotlin | 27 May 2021
    Got you, thanks. I didn’t mean to sound offensive - a better wording would be that they don’t seem to prioritize this part, at least based on https://github.com/FasterXML/jackson-module-kotlin/issues/199, which has one abandoned branch from a 3rd party and a couple of comments from from maintainers.
  • kotlinx.serialization 1.2 Released: High-Speed JSON Handling, Value Class Support, Overhauled Docs, and more
    5 projects | /r/Kotlin | 7 May 2021
    If you use Jackson, don't forget to include the Kotlin extensions https://github.com/FasterXML/jackson-module-kotlin


Posts with mentions or reviews of spring-fu. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2023-08-16.
  • What's New in Spring Framework 6.1
    5 projects | news.ycombinator.com | 16 Aug 2023
    The point isn't that one should reinvent the way that Tomcat is started, but that Spring Boot (by default) is using action at a distance and runtime reflection which have serious downsides if you want to understand what's actually going on because you're a) new to the technology, or b) have to debug some weird edge case.

    The alternative is using explicit, reflection-less code - which you can do even with Spring, although it's experimental: https://github.com/spring-projects-experimental/spring-fu

  • What are some of the biggest problems you personally face in Java?
    6 projects | /r/java | 27 Dec 2022
    Bean Definition -> Still needed although experimental projects like Spring Fu might remove their need in the future. Technically, there is nothing to stop you from registering beans functionally right now but the verbosity is likely to make that approach less optimal.
  • I hate Spring (the Java framework)
    2 projects | news.ycombinator.com | 11 Apr 2022
    Quarkus just moves the problem IMHO. I find it similarly convoluted to use as normal Spring. I had to deal with that a few months ago on a project. Honestly, it actually feels a lot like spring used to be; and not in a good way. Lots of annotation magic all over the place.

    I use Spring Boot by default. But I aggressively limit the use of annotation magic. I've never liked the byte code hacks people do to make annotations inject magical behavior. Hard to debug and painful when it does not work as expected.

    I don't think either of these frameworks have an edge over each other. You end up using a lot of the same underlying library ecosystem.

    I do like the annotation less direction that Spring has been taking since they started adding Kotlin support 4-5 years ago. If you want to, you can get rid of most annotations for things like dependency injection, defining controllers, transactions etc.

    Especially with Kotlin, this makes a lot of sense. With Java, dealing with builders is just a lot more painful without kotlin's DSL support. You basically end up with a lot of verbosity, method chaining, etc. But it's possible if you want to. It's a big reason, I prefer using Kotlin with Spring Boot. Makes the whole thing feel like a modern framework. The hard part with Spring Boot is being able to tell apart all the legacy and backwards compatible stuff from the actual current and proper way of doing things.

    There's a project that they've been pushing to get rid of all annotations: https://github.com/spring-projects-experimental/spring-fu/tr.... I suspect a lot of that stuff might be part of spring boot 3.x later this year. And quite a bit of it is actually already part of the current version of Spring.

    This makes spring boot very similar to what you'd do with ktor. All you do is call kotlin functions. No annotations. No reflection. No magic. Very little verbosity. It's all declarative. And a nice side effect is also that it makes things like spring-native easier, which they started supporting recently.

    It's very similar to using ktor with koin (for dependency injection). That combination is worth a try if you are looking for something lightweight and easy to use. Spring Boot has more features and complexity but it can be as simple to use as that if you know what you are doing.

    Mostly, keeping things simple is a good thing with Spring. Also, I don't tend to do everything the spring way. Spring integration is a bit of a double edged sword for example. It offers a subset of the features of the libraries that it integrates. If you want the full feature set, you end up working around that. IMHO, you should do that by default. I've removed spring integration from several projects.

  • Scala at Scale at Databricks
    4 projects | news.ycombinator.com | 9 Dec 2021
    > And that is a problem how? Stick to one style.

    Switching an API from "a result or nothing" to "a result or an error message" happens all the time, and switching in the other direction is only slightly less frequent. And of course most programs have some APIs where one is appropriate and some where the other is. So consistency is valuable.

    > https://github.com/spring-projects-experimental/spring-fu/tr...

    Still reflection-based.

    > There's nothing magical about it.

    It's magical to anyone thinking in the language - it breaks the rules of the language, so you can't reason about what it does.

    4 projects | news.ycombinator.com | 9 Dec 2021
    > Kotlin is an unmaintainable soup of features

    Are you sure you're not confusing Kotlin with Scala?

    > For example, Kotlin has null safety and it lets you write code using errors-as-values style "either" types - but it has two completely separate syntaxes for these things, and so it's impossible to interoperate or reuse code between those two approaches

    And that is a problem how? Stick to one style.

    > In practice Kotlin codebases still use magical incomprehensible reflection (Spring Boot)


    > and magical compile-time manipulation (Kapt)

    There's nothing magical about it.

  • A new way to construct objects in Java
    2 projects | dev.to | 16 Nov 2021
    SpringFu (from Spring team): https://github.com/spring-projects-experimental/spring-fu/tree/main/jafu
  • Annotation-free Spring
    5 projects | /r/java | 12 Sep 2021
    It's mentioned in the article, even though the examples are written in Kotlin spring-fu supports a java-based dsl.
  • Kotlin Team AMA #3: Ask Us Anything
    52 projects | /r/Kotlin | 27 May 2021
    Longer term : getting rid of kotlin-reflect in Spring Framework by performing Kotlin reflection ahead-of-time and continuing to mature https://github.com/spring-projects-experimental/spring-fu for a more DSL-ish way of configuring Spring Boot are my favorite topics.
    52 projects | /r/Kotlin | 27 May 2021
    There is already a very close collaboration between Kotlin and Spring teams. I think leveraging more multiplatform capabilities and more DSL à la KoFu from https://github.com/spring-projects-experimental/spring-fu could increase Koltin usage on server side long term.
  • The Modern Java Platform
    10 projects | news.ycombinator.com | 16 Mar 2021
    There's a next stage after annotations. The current thinking is to replace annotations with function calls. It makes more sense if you use Kotlin because Java is a bit verbose when you do this and in Kotlin you get to create nice DSLs. This cuts down on use of reflection and AOP magic that spring relies on and also enables native compilation. It also makes it easier to debug and it makes it much easier to understand what is going on at the price of surprisingly little verbosity. Kofu and Jafu are basically still experimental but work quite nicely https://github.com/spring-projects-experimental/spring-fu/tr...

    Another trend is native compilation. Spring native just went into beta (uses the Graal compiler). That still relies on reflection but they re-engineered the internals to be more native friendly.

    Spring Boot basically added the notion of autoconfiguring libraries that simply by being on the classpath self configure in a sane way. It's one of those things that makes the experience a bit more ruby on rails like. Stuff just works with minimal coding and you customise it as needed (or not, which is perfectly valid).

    Compared to XML configuration, Spring has come a long way. Separating code and configuration is still a good idea with Spring but indeed not strictly enforced. @Configuration classes can take the place of XML and if you use the bean dsl, that's basically the equivalent of using XML. Only it's type checked at compile time and a bit more readable.

What are some alternatives?

When comparing jackson-module-kotlin and spring-fu you can also consider the following projects:

kotlinx.serialization - Kotlin multiplatform / multi-format serialization

klaxon - A JSON parser for Kotlin

koin - Koin - a pragmatic lightweight dependency injection framework for Kotlin & Kotlin Multiplatform

compose-multiplatform - Compose Multiplatform, a modern UI framework for Kotlin that makes building performant and beautiful user interfaces easy and enjoyable.

avro4k - Avro support for kotlinx.serialization


mapstruct-examples - Examples for using MapStruct

KTON - Object notation in pure Kotlin!

fluid-json - A JSON library written in pure Kotlin

kotlin-json - A JavaScript Object Notation library for Kotlin JVM.

Micronaut - Micronaut Application Framework

teavm - Compiler of Java bytecode to JavaScript