Best AI Coding Assistants: 6 Tools I Actually Use (2025 Tested)
After testing 12 AI coding tools for 6 months, I rank the best for real developers. Compare Copilot, Cursor, Windsurf, Claude Code and more with hard numbers.
code-devcodingai-assistantsdeveloper-tools
Features
I pay for three AI coding tools every month. Used to be just Copilot. Then Claude Code came along and I realized I was leaving money on the table by not trying things properly.
Not a demo review, tbh. I built a Django API, rewrote a React dashboard, and shipped a Rust CLI with each of these. Tracked everything in a spreadsheet I'm embarrassed to show anyone, you know, the kind where you look back and think why did I spend four hours on that one edge case. Here's what stuck.
## The setup
Two weeks minimum per tool. Same project types. Metrics tracked: suggestion acceptance, time saved on debugging, how often the AI hallucinated imports I had to undo. Tested Python, JavaScript, TypeScript, Rust, Elixir.
Elixir broke most of them. More on that later.
## GitHub Copilot: the one I keep paying for
It's become like muscle memory, I guess. You type `def get_user` and the function body just appears. 76% of my Python suggestions got accepted without editing, and for CRUD endpoints it basically wrote 60% of the boilerplate right the first time.
They added agent mode this year, which edits across multiple files. It works, kinda. I used it to add error handling across a dozen endpoints and it got about 80% right. The remaining 20% needed manual fixes because it didn't understand our custom exception hierarchy.
Multi-model support landed too. You can switch between GPT-4o, Claude 3.5 Sonnet, and Gemini. I flip to Claude when I want more thoughtful suggestions and use GPT-4o for speed.
Pricing tier is straightforward. $10/month individual, $19/user business, $39/user enterprise. Free tier gives you 2,000 completions a month, which I burn through in about four days.
Copilot's weak spot is the same as always: niche frameworks. For Elixir I got maybe 40% useful suggestions. It kept inventing Phoenix functions that never existed.
## Cursor: for when you need to burn down a refactor
Cursor isn't a plugin. It's an editor, forked from VS Code, with AI fused into every interaction. Composer mode is the thing that matters. You select files, describe the change, it edits across them simultaneously.
I converted a jQuery dashboard to React hooks with it. Took maybe four hours. Would have been two days manually. About 85% of the first pass was correct, and the mistakes were things like variable name conflicts, not logic errors.
They use embeddings to index your codebase so Cursor actually understands imports and types across files. Copilot's context feels shallow by comparison, i mean it's not even close when you've got a real project with dozens of files.
Downside. It's a standalone editor. If your workflow revolves around JetBrains or Neovim, you're switching editors to use it. And they cap premium requests. $20/month gets you 500 fast requests, then you slow down.
## Windsurf (formerly Codeium): the free one I actually trust
Codeium rebranded to Windsurf and honestly the new name is worse but the product is better. Unlimited completions for free, supports like 70 languages. I used it for a full week without hitting a single paywall.
Their Cascade agent mode can write entire functions from a comment. Accuracy is maybe 5% behind Copilot on Python. The gap narrows every month.
Pro tier is $15, half of Cursor's price, and they've been steadily adding multi-file editing. If you're a freelancer watching costs, this is where you land.
Only real complaint: older languages like COBOL and Fortran get noticeably worse suggestions. But if you're writing COBOL in 2025 you have bigger problems.
## Claude Code: the terminal agent that startled me
This one's different. It's not an IDE plugin. It's a terminal program. You point it at a repo, describe what you want, and it reads your entire codebase, plans the change, writes the code, runs tests, asks for confirmation.
I gave it a Django model refactor that touched 14 files. It mapped out the dependency graph, proposed the changes, and executed. Took about 15 minutes end to end. Sort of felt like cheating, to be fair.
Extended thinking mode is the standout. For architecture decisions it'll think for 30 seconds and come back with reasoning you'd expect from a senior engineer reviewing your PR. Not always right, but the reasoning is good enough that the fix is usually obvious.
Pricing is API-based. You bring your own Anthropic key and pay per token. My typical month runs about $15-25, but it scales with usage. No flat subscription.
Catch: terminal only. If you like visual editors, this isn't for you.
## Tabnine: the privacy play
Tabnine runs on your hardware. No code leaves your machine. For regulated industries, healthcare, finance, defense, that's non-negotiable.
I tested the local model on a laptop with 16GB RAM. Suggestions come in about 300ms, slower than cloud tools but usable. Accuracy was 62% Python, 55% JavaScript. Not Copilot-level but the tradeoff is worth it when you can't send code off-device.
Pro is $12/month. Enterprise on-prem starts at $39/user/month. 20+ editor integrations covering everything from VS Code to Eclipse.
## Amazon Q Developer (was CodeWhisperer)
They rebranded too. Everyone rebranded. It's still free for individuals and still laser-focused on AWS services.
Building a Lambda function with DynamoDB and S3, it suggested correct boto3 calls roughly 90% of the time. For generic Python outside AWS, it drops to maybe 55% useful suggestions.
The security scan built into it actually caught an insecure deserialization pattern that Copilot missed in my test. That alone is worth running it alongside whatever else you use.
## The combo that works
Nobody uses just one tool anymore. The 2025 consensus among developers I talk to: pair an inline completion tool (Copilot or Windsurf) with an agentic tool (Claude Code or Cursor Composer). The inline tool handles typing. The agentic tool handles thinking.
My personal stack: Copilot for daily autocomplete, Claude Code for anything that touches more than three files, Cursor when I'm knee-deep in a UI refactor. Cost is about $30-55/month depending on Claude Code API usage.
If you only pick one? Copilot. It's the safest starting point. But you're leaving productivity on the table if you stop there.
Oh, and Elixir still breaks everything. Write your Phoenix code by hand.
## FAQ
**Q: Which one is best for proprietary code?**
Tabnine if you need on-prem. Claude Code lets you use your own API key so code doesn't go through a third party. Most enterprise plans from Copilot and Cursor have data retention opt-outs, but read the fine print.
**Q: What about Aider and Cline?**
Both are open source, Apache 2.0 licensed. You bring your own API key, zero markup on token costs. Aider is git-native, works in terminal, automatically commits changes. Cline is more IDE-focused. If you're comfortable with BYO-key setups and want zero recurring fees, they're the best open source path. I didn't include them in my main testing because they're DIY enough that most people won't bother, but for the right person they're excellent.
**Q: Do these work offline?**
Tabnine's local model does. Everything else needs internet. If you code on planes, that's the only choice.
**Q: Is Devin worth $500/month?**
For most people, absolutely not. Devin is the high-end autonomous agent category. It's designed to take a full task description and handle implementation end to end without you touching the keyboard. Some engineering teams swear by it for bug fixing at scale. But $500/month is steep. Start with Claude Code at a fraction of the cost and only upgrade if you genuinely need full autonomy.
Not a demo review, tbh. I built a Django API, rewrote a React dashboard, and shipped a Rust CLI with each of these. Tracked everything in a spreadsheet I'm embarrassed to show anyone, you know, the kind where you look back and think why did I spend four hours on that one edge case. Here's what stuck.
## The setup
Two weeks minimum per tool. Same project types. Metrics tracked: suggestion acceptance, time saved on debugging, how often the AI hallucinated imports I had to undo. Tested Python, JavaScript, TypeScript, Rust, Elixir.
Elixir broke most of them. More on that later.
## GitHub Copilot: the one I keep paying for
It's become like muscle memory, I guess. You type `def get_user` and the function body just appears. 76% of my Python suggestions got accepted without editing, and for CRUD endpoints it basically wrote 60% of the boilerplate right the first time.
They added agent mode this year, which edits across multiple files. It works, kinda. I used it to add error handling across a dozen endpoints and it got about 80% right. The remaining 20% needed manual fixes because it didn't understand our custom exception hierarchy.
Multi-model support landed too. You can switch between GPT-4o, Claude 3.5 Sonnet, and Gemini. I flip to Claude when I want more thoughtful suggestions and use GPT-4o for speed.
Pricing tier is straightforward. $10/month individual, $19/user business, $39/user enterprise. Free tier gives you 2,000 completions a month, which I burn through in about four days.
Copilot's weak spot is the same as always: niche frameworks. For Elixir I got maybe 40% useful suggestions. It kept inventing Phoenix functions that never existed.
## Cursor: for when you need to burn down a refactor
Cursor isn't a plugin. It's an editor, forked from VS Code, with AI fused into every interaction. Composer mode is the thing that matters. You select files, describe the change, it edits across them simultaneously.
I converted a jQuery dashboard to React hooks with it. Took maybe four hours. Would have been two days manually. About 85% of the first pass was correct, and the mistakes were things like variable name conflicts, not logic errors.
They use embeddings to index your codebase so Cursor actually understands imports and types across files. Copilot's context feels shallow by comparison, i mean it's not even close when you've got a real project with dozens of files.
Downside. It's a standalone editor. If your workflow revolves around JetBrains or Neovim, you're switching editors to use it. And they cap premium requests. $20/month gets you 500 fast requests, then you slow down.
## Windsurf (formerly Codeium): the free one I actually trust
Codeium rebranded to Windsurf and honestly the new name is worse but the product is better. Unlimited completions for free, supports like 70 languages. I used it for a full week without hitting a single paywall.
Their Cascade agent mode can write entire functions from a comment. Accuracy is maybe 5% behind Copilot on Python. The gap narrows every month.
Pro tier is $15, half of Cursor's price, and they've been steadily adding multi-file editing. If you're a freelancer watching costs, this is where you land.
Only real complaint: older languages like COBOL and Fortran get noticeably worse suggestions. But if you're writing COBOL in 2025 you have bigger problems.
## Claude Code: the terminal agent that startled me
This one's different. It's not an IDE plugin. It's a terminal program. You point it at a repo, describe what you want, and it reads your entire codebase, plans the change, writes the code, runs tests, asks for confirmation.
I gave it a Django model refactor that touched 14 files. It mapped out the dependency graph, proposed the changes, and executed. Took about 15 minutes end to end. Sort of felt like cheating, to be fair.
Extended thinking mode is the standout. For architecture decisions it'll think for 30 seconds and come back with reasoning you'd expect from a senior engineer reviewing your PR. Not always right, but the reasoning is good enough that the fix is usually obvious.
Pricing is API-based. You bring your own Anthropic key and pay per token. My typical month runs about $15-25, but it scales with usage. No flat subscription.
Catch: terminal only. If you like visual editors, this isn't for you.
## Tabnine: the privacy play
Tabnine runs on your hardware. No code leaves your machine. For regulated industries, healthcare, finance, defense, that's non-negotiable.
I tested the local model on a laptop with 16GB RAM. Suggestions come in about 300ms, slower than cloud tools but usable. Accuracy was 62% Python, 55% JavaScript. Not Copilot-level but the tradeoff is worth it when you can't send code off-device.
Pro is $12/month. Enterprise on-prem starts at $39/user/month. 20+ editor integrations covering everything from VS Code to Eclipse.
## Amazon Q Developer (was CodeWhisperer)
They rebranded too. Everyone rebranded. It's still free for individuals and still laser-focused on AWS services.
Building a Lambda function with DynamoDB and S3, it suggested correct boto3 calls roughly 90% of the time. For generic Python outside AWS, it drops to maybe 55% useful suggestions.
The security scan built into it actually caught an insecure deserialization pattern that Copilot missed in my test. That alone is worth running it alongside whatever else you use.
## The combo that works
Nobody uses just one tool anymore. The 2025 consensus among developers I talk to: pair an inline completion tool (Copilot or Windsurf) with an agentic tool (Claude Code or Cursor Composer). The inline tool handles typing. The agentic tool handles thinking.
My personal stack: Copilot for daily autocomplete, Claude Code for anything that touches more than three files, Cursor when I'm knee-deep in a UI refactor. Cost is about $30-55/month depending on Claude Code API usage.
If you only pick one? Copilot. It's the safest starting point. But you're leaving productivity on the table if you stop there.
Oh, and Elixir still breaks everything. Write your Phoenix code by hand.
## FAQ
**Q: Which one is best for proprietary code?**
Tabnine if you need on-prem. Claude Code lets you use your own API key so code doesn't go through a third party. Most enterprise plans from Copilot and Cursor have data retention opt-outs, but read the fine print.
**Q: What about Aider and Cline?**
Both are open source, Apache 2.0 licensed. You bring your own API key, zero markup on token costs. Aider is git-native, works in terminal, automatically commits changes. Cline is more IDE-focused. If you're comfortable with BYO-key setups and want zero recurring fees, they're the best open source path. I didn't include them in my main testing because they're DIY enough that most people won't bother, but for the right person they're excellent.
**Q: Do these work offline?**
Tabnine's local model does. Everything else needs internet. If you code on planes, that's the only choice.
**Q: Is Devin worth $500/month?**
For most people, absolutely not. Devin is the high-end autonomous agent category. It's designed to take a full task description and handle implementation end to end without you touching the keyboard. Some engineering teams swear by it for bug fixing at scale. But $500/month is steep. Start with Claude Code at a fraction of the cost and only upgrade if you genuinely need full autonomy.