Open vs closed models for coding agents
Updated
An open model (open-weight model) is one whose trained weights are published for anyone to download and run, while a closed model is available only through its maker's API and products.
For a coding agent the difference shows up in four places: what you pay per token, who can serve the model, whether a version can disappear, and where your code goes.
The differences that matter
| Open-weight model | Closed model | |
|---|---|---|
| Weights | Downloadable, under the license on the model card | Not published |
| Who can serve it | Any provider, or your own hardware | The maker and its partners |
| Price | Set by each provider that serves it | Set by the maker |
| Versions | Published weights stay downloadable | The maker can retire a version |
| Inspect and fine-tune | Yes | Only through the maker's tools |
| Data path | Choose a provider, or keep it in-house | Goes to the maker or its partners |
The open models on OpenScale
| Model | Maker | License | Context | Input / 1M | Output / 1M |
|---|---|---|---|---|---|
| DeepSeek V4.1 Flash | DeepSeek | MIT | 1,048,568 tokens | $0.06 | $0.24 |
| GLM 5.3 Flash | Z.ai | MIT | 1,048,576 tokens | $0.12 | $0.40 |
Both model cards on Hugging Face state the MIT license (DeepSeek V4.1 Flash, GLM 5.3 Flash). Both support tool calling and JSON output, which coding agents depend on, and both take image input.
When an open model is the right pick
- High-volume agent work, where the input bill is large and a low cached input price changes the total most.
- Work that needs a fixed version. A pinned open model behaves the same next year. On OpenScale, pinned ids such as
deepseek/deepseek-v4.1-flash-1017never change. - Teams that want a second source. If one provider has an outage, the same weights run elsewhere.
A closed frontier model can still be the right call for the hardest single tasks. You can also split the work: an open model for most agent turns, a closed one for the hardest tasks. Test both on your own repository with the same task list before you decide.
Questions
Can I use an open model in a coding agent built for a closed one?
Yes, when the provider speaks the agent's API format. Most agents accept an OpenAI-compatible or Anthropic-compatible base URL. See the compatible APIs guide.
Is "open source" the same as "open weight"?
Not always. Open weight means the weights are published; the training code and data may not be. Read the license on the model card for what you may do.