Code

Mellum

JetBrains models for fast code autocompletion. Mellum2 (12B, 2.5B active) is already a full assistant: it writes and edits code, calls tools and reasons.

Developer
JetBrains, Czech Republic
First release
Apr 2025
Latest release
Jun 2026
Sizes
4B – 12B-A2.5B
License
Commercial use allowedApache 2.0
Russian
Not supported
Ready-made builds
GGUF, MLX (Apple)
Running
On your own serverAlso runs without a GPU
Industries
Software development
Deploy on your server Hugging Face

What it does

  • Fast code autocompletion on your own server
  • A developer assistant that does not send code to the cloud
  • Fine-tuning on the company's code

Where it is used

IT departmentsProduct development

Hardware requirements

LaptopLaptop or regular PC, up to 8 GB of VRAM — smaller versions
fits
1 GPUOne GPU with 16–80 GB — mid-size versions
fits
ClusterServer with several GPUs — flagship versions
no versions

Versions

  1. Mellum2 12B-A2.5B Instruct и Thinking
  2. Mellum-4b DPO
  3. Mellum-4b SFT для Python и Kotlin
  4. Mellum-4b-base

How to run it

On your own serverWeights are downloaded from Hugging Face and served with vLLM (load and API) or llama.cpp (modest hardware). The model then runs in a closed network with no per-request fees.Hugging Face
How much hardware you needCalculate the VRAM for the model size, context length and number of concurrent requests.Open the hardware calculator

I can set this up end to end: pick the model size, deploy it on your server and connect it to your systems. Quantization compresses a model so it takes less video memory and runs on more modest hardware. Answers change slightly, so quality is checked on your own examples.

Frequently asked questions

Can Mellum be used in a commercial project?

Yes. License: Apache 2.0. It allows commercial use, but it is still worth having a lawyer review the license before launch.

What hardware does Mellum need?

At minimum: Laptop or regular PC, up to 8 GB of VRAM — smaller versions. Some versions also run on an ordinary CPU, without a GPU. You can calculate the exact VRAM for your model size and context in the hardware calculator.

Does Mellum support Russian?

No. The model card lists its languages and Russian is not among them.

Where can I download Mellum and what does it cost?

The Mellum weights are open and free to download. You only pay for the hardware it runs on and for the setup. Source links are at the bottom of this page.

How I deploy it for clients

  1. SelectionI pick the model size for your task and hardware and test it on your examples.
  2. DeploymentI deploy it on your server or in a closed network and provide an API.
  3. Fine-tuningI fine-tune it on your data (LoRA) or connect a knowledge base — whichever is cheaper for the task.
  4. IntegrationI connect it to your CRM, ERP, bot, website or team chat and set up monitoring.

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Details

Source: blog.jetbrains.com/ai/2026/06/mellum2-goes-open-source-a-fast-model-fo. Data checked against the model card on 22 Sep 2026. Have a lawyer review the license before commercial launch.