What is the main difference?

Aider is a terminal-based coding agent that commits accepted changes to git. Mellum by JetBrains is a code language model focused on low-latency completion in IDE workflows.

Which product is listed as free?

Aider is listed as free. Its underlying model cost depends on the provider's token pricing. Mellum by JetBrains has no pricing recorded.

What are Aider's main limits?

Aider has no GUI, has no inline-edit overlay like Cursor, and its cost depends entirely on the underlying provider's token pricing.

Aider vs Mellum by JetBrains: How They Actually Differ

Aider suits terminal-based developers who want an open-source, bring-your-own-key coding agent that commits accepted changes to git. Mellum by JetBrains suits developers already working in JetBrains IDEs who want fast inline code completion. Choose Aider for broader agentic editing; choose Mellum for a narrower completion workflow.

Compiled 2026-10-24 from our catalogue entries for Aider and Mellum by JetBrains.

The short answer

Pick Aider if: You work in a terminal, want bring-your-own-key support for OpenAI, Anthropic, Gemini, DeepSeek, or local Ollama models, and want every accepted change committed to git with a generated message.
Pick Mellum by JetBrains if: You already work in JetBrains IDEs and want low-latency inline code completion through the JetBrains AI Assistant plugin.
Cheapest way in: Aider is listed as free. Mellum by JetBrains has no pricing model or starting price recorded, so the sheet does not support a cost comparison.
What we could not compare: Mellum by JetBrains has no recorded pricing, starting price, or platform information. Neither product has docs listed, and no verified plans are on file for either.

Aider is an open-source CLI coding agent that pair-programs in your terminal and commits each accepted change to git automatically. It is fully open source under Apache 2.0, has no vendor lock-in, and supports bring-your-own-key use across OpenAI, Anthropic, Gemini, DeepSeek, and local Ollama models. Its cost depends on the token pricing of the underlying provider.

Mellum by JetBrains is an open-source code language model released by JetBrains on Hugging Face. It is purpose-built for low-latency code completion in IDE workflows and integrates with JetBrains IDEs through the JetBrains AI Assistant plugin. It focuses on completion rather than broader agentic coding tasks, and its capability breadth is narrower than larger frontier code models.

Side by side

Every cell is a field on our catalogue entry for that tool, copied as recorded. Rows where the two differ come first; blank fields say so rather than being filled in.

	Aider	Mellum by JetBrains
Pricing model	Free	Not recorded
Starts at	Free	Not recorded
Runs on	mac, win, linux, cli	Not recorded
Public source code	Yes — public repo	No public repo listed
Category	AI Coding Agents	AI Coding Agents
Public docs	Not listed	Not listed

Public source code: From the repository link on each catalogue entry, not a licence audit.

Where Aider is the better fit

Fully open source under Apache 2.0, with no vendor lock-in.
Offers bring-your-own-key support for OpenAI, Anthropic, Gemini, DeepSeek, and local Ollama models.
Commits every accepted change to git with a generated commit message.

Full Aider entry

Where Mellum by JetBrains is the better fit

Open-source code language model released by JetBrains on Hugging Face.
Purpose-built for low-latency code completion in IDE workflows.
Integrates with JetBrains IDEs through the JetBrains AI Assistant plugin.

Full Mellum by JetBrains entry

Which one should you pick?

Solo founder working mainly in a terminal

Aider

It combines model-provider choice with automatic git commits for every accepted change.

Developer already using JetBrains IDEs

Mellum by JetBrains

It is purpose-built for low-latency inline completion in JetBrains IDEs through the JetBrains AI Assistant plugin.

Frequently asked questions

What is the main difference?: Aider is a terminal-based coding agent that commits accepted changes to git. Mellum by JetBrains is a code language model focused on low-latency completion in IDE workflows.
Which product is listed as free?: Aider is listed as free. Its underlying model cost depends on the provider's token pricing. Mellum by JetBrains has no pricing recorded.
Which option has an explicit JetBrains IDE integration?: Mellum by JetBrains integrates with JetBrains IDEs through the JetBrains AI Assistant plugin. Aider is command-line only.
What are Aider's main limits?: Aider has no GUI, has no inline-edit overlay like Cursor, and its cost depends entirely on the underlying provider's token pricing.
What are Mellum by JetBrains' main limits?: It focuses on code completion rather than broader agentic coding tasks, and its capability breadth is narrower than larger frontier code models.

What we compared

This page states nothing that is not in the two catalogue entries below. The exact text used to write it is reproduced here so you can check our reading, and both tools link through to their own pages and to the vendor.

/tools/aider — checked 2026-05-25 · official site
/tools/mellum-by-jetbrains — checked 2026-06-21 · official site

Show the source text

## Aider (/tools/aider)
Tagline: Open-source CLI coding agent that pair-programs in your terminal and commits to git automatically.
Category: AI Coding Agents
Pricing model: free
Starts at: Free
Platforms: mac, win, linux, cli
Public repo: https://github.com/Aider-AI/aider
Docs: none listed
Verified plans: none on file
Strengths on file: Fully open source under Apache 2.0; no vendor lock-in.; Bring-your-own-key for OpenAI, Anthropic, Gemini, DeepSeek, and local Ollama models.; Every accepted change is committed to git with a generated message.
Limits on file: No GUI — command-line only; no inline-edit overlay like Cursor.; Cost depends entirely on the underlying provider's token pricing.
Aider is an open-source CLI coding agent that pair-programs in your terminal and commits each change to git automatically.
Its edge is openness and git discipline: Apache-2.0 with no lock-in, bring-your-own-key across OpenAI, Anthropic, Gemini, DeepSeek, and local Ollama models, and every accepted change landing as a git commit with a generated message.
It fits developers who live in the terminal and want a model-agnostic agent tied to version control. The trade-offs: there's no GUI or inline-edit overlay like Cursor's — it's command-line only — and cost tracks whatever provider's token pricing you bring.
It's the open, BYOK terminal agent next to Anthropic's Claude Code and IDE-native Cursor.

## Mellum by JetBrains (/tools/mellum-by-jetbrains)
Tagline: Fast LLMs for low-latency and high-performance workflows
Category: AI Coding Agents
Pricing model: not recorded
Starts at: Not recorded
Platforms: not recorded
Public repo: none listed
Docs: none listed
Verified plans: none on file
Strengths on file: Mellum is an open-source code language model released by JetBrains on Hugging Face.; It is purpose-built for low-latency code completion in IDE workflows.; It integrates with JetBrains IDEs through the JetBrains AI Assistant plugin.
Limits on file: It is focused on code completion rather than broader agentic coding tasks.; Its capability breadth is narrower than larger frontier code models.
Mellum by JetBrains is an open-source code language model, released by JetBrains on Hugging Face, built for low-latency code completion in IDE workflows.
It is purpose-built for low-latency completion rather than general chat, and it integrates with JetBrains IDEs through the JetBrains AI Assistant plugin.
It fits developers already in JetBrains IDEs who want fast inline completion. It is not aimed at broader agentic coding, since it targets completion rather than agent tasks, and its capability breadth is narrower than larger frontier code models.

Change log

2026-10-24 — First published, compiled from the catalogue entries for Aider and Mellum by JetBrains.