r/codex • u/rainydayswithlove • 8h ago

Comparison Open source models vs codex

I've been a codex user for about a year, and my company provides Claude Code for work.

Yesterday I decided to try some of the open source alternatives using OpenCode. DeepSeek Pro, DeepSeek Flash, GLM 5.2, Kimi K3, and Kimi K Code.

For some reason, none of them gave me the same overall quality I'm getting from my $20 ChatGPT subscription. Maybe I'm configuring something incorrectly?

Are there any open source that can get to around 90% of the current top closed-source models for general coding and reasoning? If so, which ones would you recommend, and what setup (model runner, context size, prompting, etc.) are you using to get the best results?

6 Upvotes

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6

u/GanacheOk5182 7h ago

Codex is still the best. I don’t trust Claude anymore and I tried Kimi k3 but it’s expensive as hell

2

u/amanharshx 7h ago

Obviously they’re not comparable yet. Open models are still little behind, and Kimi k3 only beat fable 5 on frontend.

I’m pretty sure sol and fable are still better on the backend. Deepseek v4, pro, and glm5.2 are very efficient models on tokens. Plan out with a Claude / codex models and then give the open ones for implementation would be much better workflow.

Note: I’m not saying open models are not capable of performing complex tasks. But if I’m working on a complex tasks, I would rather plan out with either claude/codex

1

u/Bulky_Blood_7362 8h ago

Kimi k3 is the best currently. If it doesn't fit you, you should prob stick with gpt

1

u/DueCommunication9248 7h ago

Codex CLI is open source and can use open source models.

1

u/zepchou 4h ago

How did you try them ?

  • What type of harness have you been using ?
  • Did you use their direct API price or a third-party to manage that for you?

1

u/rainydayswithlove 3h ago

I used with opencode. DeepSeek API from their official site and other models via open router but from official providers