Deepseek launches an improved V4 Pro model, raises API prices, and makes its agent software open source

Deepseek has moved its flagship product out of the testing phase, released its proprietary agent software as open source, and announced higher API prices at the same time. The deepseek-v4-pro endpoint now delivers build V4-Pro-0813.

The model name, parameter count, and one-million-token context window remain unchanged, and Deepseek says existing integrations will keep running without any tweaks. In the app and on the web, the model is available under “Expert Mode.” A new addition is native support for the OpenAI Responses API with Codex integration. Reasoning effort can be set to three levels: “low,” “high,” and “max,” with Deepseek recommending the middle setting for everyday agent use. According to Deepseek’s own comparison table, Terminal Bench 2.1 scores jumped from 72.1 to 87.9, and DeepSWE scores went from 12.8 to 62.7. On several agent benchmarks, the model beat Claude Opus 4.8.Ad Artificial Analysis backs up the improvement but also puts it in context. V4-Pro climbs from 45 to 53 on the Intelligence Index, tying GLM-5.2. That’s still behind Muse Spark  at 57, Qwen 3.8 Max at 58, and Kimi K3 at 60. Claude Opus 5 sits at the top with 63 points. Deepseek hasn’t published the weights for the new build yet, and the April preview version is still up on Hugging Face.Ad The update was also a response to the smaller V4 Flash model closing in on the flagship. At the end of July, Deepseek shipped update 0731 for V4 Flash, which practically matched the Pro Preview on the Artificial Analysis Intelligence Index while costing a fraction of the price. Alongside the model update, Deepseek Harness v0.1 is shipping as a Developer Preview under the MIT license. The open-source agent software is pitched as an alternative to OpenAI’s Codex and Claude. It’s built on the newly released Cordis plugin system, where all features are swappable plugins, from tools and sandboxes to sessions and the UI. A continuous session log tracks every prompt, every tool call, and every result. Runs can be resumed, branched, and replayed.Ad Minimal mode strips things down to the shell and file editor, and Deepseek uses this setup for its own benchmark runs.