← ChatGPT & Codex changelog

OpenAI API — August, 2026

This release delivers significant performance and cost improvements, introducing an Ultrafast mode for GPT-5.6 Sol and lowering its pricing by up to 33%. Developers gain a new Prompt Caching dashboard for optimization and expanded data control with regional processing. Security professionals benefit from new Daybreak access tiers, while image generation now supports transparent backgrounds. Users should note upcoming deprecations for transcription models and the Assistants API.

Added

  • Released the Prompt Caching dashboard on the OpenAI API platform. Track your cache hit rate over time, cache reads per write, and the breakdown of cache-read, cache-write, and uncached tokens to understand your caching efficiency and identify opportunities to improve. Filter metrics by model and service tier.
  • Announced Ultrafast mode, a new API service tier for GPT-5.6 Sol that runs up to 14x faster than Standard processing. Available in limited preview to select customers. Sign up to receive updates on Ultrafast mode here.

Changed

  • Announced the deprecation of whisper-1, gpt-4o-transcribe, gpt-4o-mini-transcribe, and gpt-4o-transcribe-diarize. These models will shut down on February 26, 2027. Migrate to gpt-live-transcribe or gpt-transcribe. See the transcription guide and deprecations page.
  • The Assistants API shut down on August 26, 2026. Migrate to the Responses API and Conversations API using the migration guide.
  • API customers can now select regional processing for an individual request by using a prefixed domain with an API key from a project having Global geography. Existing eligibility, data retention control, endpoint, and model support requirements continue to apply. Learn more in the data controls guide.
  • GPT-5.6 Sol now costs $4 per million input tokens and $20 per million output tokens, representing 20% lower input pricing and 33% lower output pricing. GPT-5.6 Sol’s promotional pricing is available at least through November 21, 2026. See pricing details.
  • Transparent backgrounds are now available in preview for gpt-image-2 and gpt-image-2-2026-04-21 in the Images API and the Responses API image generation tool. Set background to transparent and use png or webp output; jpeg does not support transparent backgrounds. Learn more in the image generation guide.
  • Start with Daybreak Blue for most defensive security work. It provides access to general-purpose models such as GPT-5.6 Sol for vulnerability discovery, secure code review, detection engineering, incident response, malware analysis, and patch validation. Read more here.
  • Daybreak Red provides separately approved access to purpose-trained models such as GPT-5.6 Cyber for authorized vulnerability reproduction, exploit validation, penetration testing, red teaming, and complex system analysis.
  • These models require separate approval and provisioning. You can apply to join the Daybreak program here. More details on pricing here.
  • Updated the chat-latest snapshot, which points to the latest model available in ChatGPT for Plus and Pro users. We recommend leveraging GPT-5.6 Sol for production API usage, but feel free to use this model to test the latest improvements for chat use cases. The underlying model snapshot will be regularly updated. Read more here.
  • Fast mode now supports long-context requests for GPT-5.6 Sol, GPT-5.6 Terra, and GPT-5.6 Luna. As of today, long-context prompts exceeding 272K tokens can run in Fast mode, delivering speeds up to 2.5× faster than the Standard tier. See pricing details.
  • Customers can now filter and group data by API key in the Usage and Costs dashboards. The Usage API and Costs API also support the API key dimension for programmatic reporting and analysis.

Fixed

  • Daybreak now offers two access tiers for approved defenders: Daybreak Blue and Daybreak Red. Use them to move from security findings to validated fixes in explicitly authorized engagements.