September 21, 2026
Reasoning models are free to try: LangChain hosts open SemIf for a week
Open SemIf is already available in LangSmith Gateway: switching to it takes one line in the TypeSafe SDK.
Harrison Chase
@hwchase17
jev is a new type of model, “reasoning models” there are already several open alternatives, one of them is SemIf (based on Qwen3.5) we are hosting SemIf ourselves and giving it away free through LangSmith Gateway all next week!
🆓 Free Open-Source Jev 🤝 LangSmith Gateway Decision models are becoming a first-class part of the LangSmith Gateway! We're serving SemIf, an open-source decision model, free for the next week. Compatible with the TypeSafe SDK - just change a string to try it! Docs in 🧵
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A whole class of models is being offered free for a week. An open alternative to jev is already available in the LangSmith gateway.
Reasoning models are presented as a separate type of model, rather than just another chat-model mode. jev already has several open alternatives, and LangChain has taken on hosting one of them.
What changes in code. SemIf is compatible with the TypeSafe SDK: switching takes one line. Reasoning models in LangSmith Gateway now sit alongside standard ones as a native option.
Before and now. Previously, LangSmith Gateway carried standard models, with no reasoning models in it. Now SemIf is in the shared list, and it is free for a week starting 21.09.2026.
SemIf is open and built on Qwen3.5, so the free week is not the only way to access it.
The free window in LangSmith Gateway closes on 28.09.2026.
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