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Meta's Muse Spark Delayed as Developer API Stays in Partner Testing

The setback risks slowing Meta's shift to closed, paid models and leaves revenue and developer adoption contingent on a stable public API.

Overview

  • Muse Spark launched for internal use on April 8, 2026, as the first major model from Alexandr Wang’s secretive Superintelligence/TBD Lab.
  • The public developer API has been repeatedly postponed because reporters say engineers found persistent software bugs and infrastructure problems that block wider access.
  • Meta says the API is being tested by a small group of partners and expects a broader rollout this month, but it has not published a firm launch date.
  • Muse Spark is closed-source and uses parts of Meta’s existing Llama code and datasets, a deliberate move that makes controlled API access central to Meta’s plan to earn money from the model.
  • Inside Meta staff praise Muse Spark’s visual and health-related capabilities but say it trails rivals on coding tasks, a gap that has heightened internal disagreements and investor pressure to show commercial results.