👩💻 AI for Developers, by Developers: JetBrains Enters the Chat with Mellum

Mellum: JetBrains' Open-Source AI Coder Is Here – But Is It Secure Enough? 🤖💻

JetBrains, the company best known for giving developers smart tools like IntelliJ IDEA and PyCharm, just dropped something that could reshape the way we code — and teach coding.

Meet Mellum — their first open AI model for code generation.

Built with 4 billion parameters and trained on over 4 trillion tokens (that’s roughly the equivalent of 120 billion lines of code), Mellum is now available on Hugging Face under an open Apache 2.0 license. That’s big news for developers, researchers, educators, and AI tinkerers alike.

But while JetBrains is proudly waving the "open model" flag, there’s more to unpack than just the release itself. Mellum is powerful, yes — but also incomplete, raw, and potentially vulnerable.

So, what exactly is Mellum? What’s in it for the dev community? And what should we be watching out for?

🔍 What is Mellum and Why Does It Matter?

Mellum is a code-completion AI model, meaning it can help finish your code based on what you’re typing — kind of like a supercharged autocomplete system built specifically for software development. It’s JetBrains’ entry into a space already buzzing with AI coders like GitHub Copilot, CodeWhisperer, and Tabnine.

But here’s what makes Mellum different:

• It’s open source: You can download it, inspect it, fine-tune it, and build on top of it.
• It’s task-focused: JetBrains isn’t chasing general AI; they’re focused purely on improving the coding experience.
• It’s customizable: Mellum isn’t a plug-and-play tool. You need to fine-tune it first, which also means you can shape it to your own development workflows.

💡 How Was Mellum Built?

JetBrains trained Mellum on a mix of permissively licensed code from GitHub and public text data like Wikipedia articles. It ran for 20 days straight on 256 Nvidia H200 GPUs — serious firepower for a serious AI.

If you’re wondering what "4 trillion tokens" actually means, think of it like this: 1 million tokens = about 30,000 lines of code. So Mellum has seen enough examples to cover a lot of programming patterns, syntax quirks, and edge cases.

Right now, JetBrains is releasing a few fine-tuned models focused on Python, but the base model is language-agnostic and can be fine-tuned for other languages like Java, JavaScript, and C++.

🚧 But… It’s Not Ready for Production Yet

Here’s the key caveat: Mellum is not production-ready. Even JetBrains says it themselves.

“These models are meant for experimentation, not production deployment.”

Translation: Mellum still has bugs, biases, and security holes.

That’s not a surprise. A survey from developer security platform Snyk found that more than 50% of companies report encountering security issues when using AI-generated code. And since Mellum was trained using publicly available repositories, it may have "learned" bad practices or outdated patterns.

So, should you build your next SaaS platform using code from Mellum? Probably not yet.

But if you’re a researcher, educator, or a developer exploring AI augmentation, this could be a treasure trove.

🧠 A Tool for Learning and Research

JetBrains is pitching Mellum as a research and education-first tool. They want developers and students to explore:

• How AI models understand and generate code.
• How to fine-tune models to match specific languages or frameworks.
• How to test for security, bias, and performance in code generation.

Think of Mellum not as a product, but as a foundation.

JetBrains even said in their blog:

“We’re not chasing generality — we’re building focus. If Mellum sparks even one meaningful experiment, contribution, or collaboration, we would consider it a win.”

That’s a bold but humble move — one that could bring more transparency and innovation into AI-assisted development.

🔐 Security: The Elephant in the Server Room

Let’s not sugarcoat it: AI-generated code isn’t always secure.

Mellum is no exception. JetBrains openly admits that it may reflect biases in public code and that it won’t guarantee vulnerability-free suggestions. This issue is already biting major players — remember when AI tools were found to leak private keys, passwords, and even license violations?

This raises some important questions:

• Who is responsible when AI-generated code has a security flaw?
• Should companies use open AI coders if they haven’t undergone full security audits?
• Can AI-generated code ever really match human code review?

🌍 Why Open Source AI Models Like Mellum Matter

In a world dominated by proprietary black-box models like OpenAI’s Codex or Google’s Gemini Code Assist, an open model like Mellum is refreshing.

Why?

Because it enables:

• Transparency: Researchers can peek inside and understand how the model makes decisions.
• Customization: Developers can fine-tune it for specific coding styles or rules.
• Education: Students and learners can tinker with real-world AI models.

And most importantly — it levels the playing field. Not every company can afford premium AI services from Microsoft or Amazon. Open tools like Mellum democratize access.

🧵 Critical Questions to Spark a LinkedIn Discussion:

1. Will open-source code AIs like Mellum accelerate innovation — or security risks?
2. How should companies train their dev teams to safely use AI-generated code?
3. Do you think AI coders will ever replace junior developers? Or are they simply the new "Stack Overflow"?
4. Can open models compete with proprietary giants like GitHub Copilot in quality?
5. Should open models be certified for safety before release?

Let’s talk 👇

📈 Final Thoughts: Mellum’s First Step, Not Its Final Form

JetBrains’ launch of Mellum is exciting not because it’s perfect — but because it’s open, focused, and invites collaboration.

As AI continues to shape software development, Mellum reminds us that community-driven tools still matter, especially when we need trust, flexibility, and innovation.

So whether you’re a coder, educator, security pro, or researcher — Mellum gives you something you can build with, not just build on.

Let’s hope it inspires more AI companies to share their work — not just sell it.

Join me and my incredible LinkedIn friends as we embark on a journey of innovation, AI, and EA, always keeping climate action at the forefront of our minds. 🌐 Follow me for more exciting updates https://lnkd.in/epE3SCni

#AIForDevelopers #OpenSourceAI #JetBrainsMellum #AIInCoding #SecureAI #CodeCompletion #AIInSoftwareEngineering #DeveloperTools #HuggingFace #MellumModel #AIResearch #FutureOfCoding #OpenAIModels #CodingWithAI #MachineLearning #AIandSecurity #TechEthics #AIInnovation #OpenSourceTools #DevCommunity

Reference: Tech Crunch