OpenJev Reverse-Engineers TypeSafe's Classifier Inference, Then Renames Itself SemIf Mid-Launch

OpenJev / SemIf / Hacker News (638pts, 270 comments)·medium signalXBlueskyLinkedInCopy link

OpenJev hit 638 points and 270 comments on September 18 as an open reimplementation of TypeSafe's proprietary Jev, which skips decoding entirely and returns calibrated probabilities over predefined options during the prefill pass, claimed at 40 to 200 times faster than a frontier LLM for structured decisions. By the time I fetched the site it had already renamed to SemIf and added a disclaimer that it is "not affiliated with or endorsed by TypeSafe", publishing accuracy per backing model (Qwen3 0.6B at 44.0-52.8%, MiniCPM5 2B at 68.6-69.3%) against a published Jev figure of 88.3%. Commenters hit it hard on a vibecoded landing page and on one tester's report of inconsistent probabilities across models.