Vibe Coding with Elixir/Phoenix

#elixir #phoenix #vibecoding

Intro

I run a startup with 4 members, a full time member and 3 others are part-time (one support for business strategy & documents). It's so hard for us with a ton of tasks (we build a quite big system with numbers of services). We try some ways for speed up development time but still overload for us (limited resources).

Before go to vibe coding I used Copilot (premium version) for almost thing is suggestion and it quite good for this, much better than Language Server. From my view, Copilot can improve my performance around 10-15%.

When we start to build DiSport project, LLM model is still in early stage and limitations for coding (especially for Elixir). After couple years, I see it a lot of improvements for coding and vibe coding is booming then I went to try vibe coding with our project (write by Elixir & Flutter).

Go to vibe coding

The first try, I start with our web site https://ohhi.vn. I tried to improve UI for people can easy to read our post on that. I setup a AI agent with Gemini from Google and setup MCP servers for that. After couple hours our site have totally new UI with much more beautiful & look modern. Agent can run test, migration & compile then fix bugs from our project. Some time it make mistake and loop then a fix with small change then agent can continues task.

The second try, I go to with both Claude Code & Gemini. I see Claude is good for integrating with Zed and CLI is run faster than Gemini (but Gemini has nice & easy to track change from agent). About Elixir Claude Code is done good than Gemini but I think with UI and work with HEEX template Gemini do better.

The third try, I try to build all new service by Claude Code, I don't give agent run full script just step by step for easy tracking what happen. I make new Phoenix project and add Tidewave, UsageRules and config Zed for this repo. Agent is speedup my process much more than anything else, I think at least x3 time when compare with I coding without agent and just using Copilot for suggestion.

I have plan to build our agent for other task by Jido and think again about new way for user interactive with our application.

Cost of vibe coding

I try to build a local LLM with my old PC + couple of GPUs (24 VRAM) that is enough for LLM with 30B (Q4) to run. It's fast for generating new skeleton project but for big project like our it too slow then I go to third party services. For who want to build local LLM I think LLM with 70B enough for almost tasks.

For Gemini, it's quite expensive for us. I spend about around 300$ for improve UI task.

For Claude Code, I see it's cheap than Gemini.

I also try other providers but these are limited their services for Vietnam then I don't use!

Conclusion

Vibe coding is good for experience dev & help any company can save cost & time to develop product. Startups with limited resources are get a lot of benefit from vibe coding.

Vibe coding is totally change our way to develop prod but it has a downside that is new member (with limited knowledge about system & skill is weak) can't catch up process & other members.

Configs I used: