A stealth model called Union Alpha appeared free on OpenRouter on September 16

OpenRouter API (via r/singularity, 401 upvotes)·medium signalXBlueskyLinkedInCopy link

OpenRouter's model API now lists stealth/union-alpha, created 2026-09-16 at 14:42 UTC, priced at zero for both prompt and completion, 262,144-token context with 131,072 max completion tokens, text+image input, tool calling and response_format supported, and is_moderated false. Its own description calls it "a multimodal model built for research, coding, and agentic workflows" delivering "frontier-level performance," with the lab unnamed. The r/singularity thread (401 upvotes) guesses Kimi. Free frontier-class inference with a 256K window and working tool support is worth grabbing while the evaluation window is open, since stealth listings historically get pulled within days.