OpenAI Models Release Notes (2026, Living Document)

A timeline of OpenAI's 2026 model and API releases. Every entry carries its source and check date: regular entries quote the changelog verbatim (last successful fetch 2026-09-01); when the docs domain is unreachable, entries cite official SDK release notes and are labelled as such.

Operating model: we re-fetch developers.openai.com/api/docs/changelog weekly, append new entries, and update dataSourcedAt. When this page disagrees with the official changelog, the official one wins.

2026-09 (latest)

Source note: the official changelog domain has returned 403 to this site since 2026-09-02 (last successful fetch 2026-09-01; re-checked and still unreachable on 2026-09-15, 09-17, and 09-19), so entries in this section draw on the official GitHub SDK release notes and type sources, each checked against the source; changelog quotes and GA status will be back-filled once reachable.

• 2026-09-18: The official SDK feature batch + Codex 0.155 stable (openai-python v3.15.0 / v3.16.0 / v3.16.1 / v3.16.2, openai-node v7.18.0 / v7.19.0; Codex CLI rust-v0.155.0 / rust-v0.155.1): prompt_cache_options gains prewarm warming (default false; true prepares the cache without generating output and forces the WS generate field to false); a new top-level client.webhooks resource (seven operations around POST /webhook_endpoints, 18 subscribable event types, signing_secret returned in plaintext only on create and rotate); the MCP tool connector_id marked deprecated (for models released after 2026-09-01 — migrate to server_url or tunnel_id); managed Responses WebSocket sessions in both languages (lane routing + final-response collection); client.beta.agents.sessions.update accepts model settings for subsequent turns; the Responses model union adds gpt-audio-mini / gpt-audio-mini-2025-12-15; python v3.15.0 catches up on the compaction progress event (aligning with node v7.17.0, #3866); on the Codex side, experimental /voice enters the TUI and Touch ID can verify MCP requests, with 0.155.1 restoring none as the reasoning-summary default. See openai-python 3.15/3.16 and openai-node 7.18/7.19: Cache Prewarming, Webhook Management, connector_id Deprecation and Codex CLI 0.155, Explained: Experimental /voice, Touch ID for MCP Requests, and the 0.155.1 Revert.

• 2026-09-16: openai-node v7.17.0 adds the compaction progress event — response.compaction.compacting: while the server processes a compaction_trigger input item it reports compaction progress at most once every 30 seconds, carrying no summary content and not modifying the compaction output item (completion is still marked by output_item.done with the final encrypted content, and a short compaction may emit no progress event at all); the WebSocket variant adds an optional stream_id and the beta multi-agent variant an optional agent.agent_name. Not landed on the Python side as of v3.14.1 (09-15) — closed on 09-18 by python v3.15.0, see the entry above. See The Responses API Compaction Progress Event: response.compaction.compacting and compaction_trigger.

• 2026-09-14 / 09-15 / 09-16: The official SDK reliability wave (openai-python v3.14.0 / v3.14.1, openai-node v7.16.0 / v7.17.0): Python normalizes stream consumption exceptions (read timeouts raise APITimeoutError, other httpx failures raise APIConnectionError; streams are never auto-retried), stringifies APIStatusError.code (404 → "404"), validates max_retries before the request (non-negative integer; 0 disables retries), and stops structurally parsing non-final_answer phases (commentary) in responses.parse; Node adds maxBufferedEvents backpressure to WebSocket iterators (overflow sheds the backlog and rejects next() with WebSocketError), flushes a terminal SSE event missing its trailing blank line exactly once at EOF, and rejects function-backed API keys without a resolved credential at WebSocket construction. See openai-python 3.14.x and openai-node 7.16/7.17: Stream Error Normalization, WebSocket Backpressure, and SSE Fixes.

• 2026-09-09 / 09-10: GPT-6-Astra becomes selectable (Codex CLI 0.154.0, 2026-09-09T22:35 UTC) — release notes verbatim: "GPT-6-Astra is now available in the model picker and Amazon Bedrock catalogs". The model picker ranks it first (models.json priority=1, with the GPT-5.6 trio dropping to 6-8; PR #42879); the Bedrock catalogs carry openai.gpt-6-astra with global and US cross-region variants (PR #42619); the bundled official migration guide (PR #42931, replacing the GPT-5.6 Sol edition) confirms Responses API calls with model: gpt-6-astra: six reasoning efforts from low to ultra (ultra = automatic task delegation; none unsupported), async tool calling, mid-turn steering over WebSocket, and configuration_update mid-conversation effort changes. Codex metadata lists a 272K context with an 872K experimental cap. Role mapping: Sol→Astra, Terra/Luna retained; no pricing figure in any loadable channel as of 2026-09-15. See GPT-6-Astra Goes Live: Codex Model Picker and Amazon Bedrock Catalogs.

• 2026-09-10: Codex SDK 0.154.0 stable (Python openai-codex / TypeScript @openai/codex-sdk; npm latest checked 2026-09-15) — the reasoning ladder gains max and ultra above minimal/low/medium/high/xhigh (the TypeScript seven-value type has no none; the official Python example's REASONING_RANK lists nine names from none to ultra); ExternalMessage: untrusted content from other agents, tools, or services enters a turn with tool-level authority, never user authorization, requiring CLI 0.151.0+; include_turns / turn_service_tier / source options; HookMetadata access moves under .root. The same CLI release adds experimental worktrees (--worktree / /worktree) and inline Q&A during running tasks, and removes the codex mcp-server entry point. See Codex CLI 0.154.0 and SDK 0.154.0: Worktrees, ExternalMessage, and the ultra Reasoning Effort.

• 2026-09-10: The Live API enters the official SDK types (openai-python v3.12.0 at 17:28 UTC / openai-node v7.14.0 at 17:29 UTC, "Add Live API") — a client.live namespace where POST /live/sessions submits a WebRTC SDP offer and a WebSocket connect() path; the sessions subresource carries the four SIP call-control endpoints (accept / reject / hangup / refer) plus fork and download_recording, and sideband attaches to an existing session. The session-config model field gains the literal gpt-live-1 (not in the ChatModel enum, not an announced model). Availability and pricing unannounced as of 2026-09-11. See The Live API lands in the OpenAI SDK: gpt-live-1, dual WebRTC/WebSocket channels, and SIP call control.

• 2026-09-10: The Agents API enters the official SDK types (openai-python v3.13.0 / openai-node v7.15.0, the same minute at 19:37 UTC, "add Agents API") — the beta namespace client.beta.agents with top-level HTTP endpoints /agents and /vaults: four resource surfaces spanning reusable Agent CRUD, Managed Agents sessions (status machine idle / in_progress / requires_action / failed), execution environments (templates / files / skills / plugins), and credential vaults. Fifteen days after the Assistants API shutdown (2026-08-26), with no official statement on the relationship. Availability and pricing unannounced as of 2026-09-11. See The Agents API appears in the OpenAI SDK (beta): /agents CRUD, environments, sessions, and vaults.

• 2026-09-08: The two GPT Image 2.5 models enter the official SDK types — gpt-image-2.5-sunburst and gpt-image-2.5-flare (each with a -2026-09-08 snapshot). quality gains xhigh / max on top of low / medium / high; transparent background no longer carries the preview note on 2.5 (gpt-image-2 still carries it); pricing and the models' positioning split were unverified that day. See GPT Image 2.5 Explained: sunburst and flare, xhigh/max Quality, Arbitrary Resolutions.

• 2026-09-08 / 09-09: Four SDK releases in two days (openai-python v3.9.0 / v3.10.0, openai-node v7.11.0 / v7.12.0): prompt cache diagnostics (prompt_cache_options.comparison_response_id → prompt_cache_diagnostics, cache_miss with 9 reason values), Service Account API key expiry fields (expires_in_seconds / expires_at), and documented 429 / 503 rate-limit and overload responses. See openai-python 3.9/3.10 and openai-node 7.11/7.12: Prompt Cache Diagnostics, API Key Expiry, GPT Image 2.5.

2026-08

Fetched from the official changelog on 2026-09-01, each entry checked verbatim.

• 2026-08-29 — Mutual TLS (mTLS) and X.509 workload identity federation are now generally available for the OpenAI API. Certificates and X.509 identity providers are configured in the Platform console, with access controlled by org roles and permissions.
• 2026-08-26 — Four transcription models announced deprecated (whisper-1, gpt-4o-transcribe, gpt-4o-mini-transcribe, gpt-4o-transcribe-diarize); shutdown on 2027-02-26, migrate to gpt-live-transcribe / gpt-transcribe. The Assistants API shut down the same day; migrate to the Responses API / Conversations API.
• 2026-08-21 — GPT-5.6 Sol price cut to $4/$20 per MTok (input -20%, output -33%); promotional pricing at least through 2026-11-21. Same day: per-request regional processing (prefixed domain + Global geography project API key).
• 2026-08-20 — Prompt Caching dashboard released (hit rate over time, cache reads per write, cache-read/write/uncached breakdown, filterable by model and service tier). Same day: gpt-image-2 transparent backgrounds enter preview (background=transparent, png/webp; jpeg unsupported).
• 2026-08-13 — Ultrafast mode announced -- a GPT-5.6 Sol-only API service tier, up to 14x Standard, limited preview.
• 2026-08-07 — Daybreak tiers -- Daybreak Blue (general-purpose models such as GPT-5.6 Sol, defensive security work) and Daybreak Red (separately approved, purpose-trained models such as GPT-5.6 Cyber, authorized pentesting and more).
• 2026-08-06 — chat-latest snapshot updated; OpenAI still recommends GPT-5.6 Sol for production API usage.
• 2026-08-05 — Fast mode gains long context -- all three tiers can run prompts beyond 272K tokens in Fast mode, up to 2.5x Standard.
• 2026-08-04 — Usage and Costs dashboards gain the API-key dimension; the Usage API and Costs API support it too.

2026-07

• 2026-07-09 — Released the GPT-5.6 model family, including GPT-5.6 Sol, GPT-5.6 Terra, and GPT-5.6 Luna.

  • Impact: supersedes the 2024-2025 mix of GPT-4o / o1 / o3 / GPT-4.1 / GPT-4.5. Three tiers share 1.05M context + 128K output + knowledge cutoff 2026-02-16; depth is now controlled continuously via reasoning.effort.

• 2026-07-06 — Released GPT-Realtime-2.1 and GPT-Realtime-2.1 mini.

  • Impact: voice flagship refresh; mid-conversation tool use stabilised; WebRTC / WebSocket supported.

2026-06

• 2026-06-01 — GPT-5.4 and GPT-5.5 added to Amazon Bedrock.
• 2026-06-02 — Container sessions billing changed: "Eligible container sessions will be billed per minute with a 5-minute minimum, instead of being billed at the full 20-minute session rate."
• 2026-06-03 — Announced the deprecation of reusable prompt objects, the Evals platform, and Agent Builder.
• 2026-06-24 — Updated the chat-latest snapshot.

2026-05

• 2026-05-05 — Released chat-latest snapshot.
• 2026-05-07 — Released GPT-Realtime-2, GPT-Realtime-Translate, and GPT-Realtime-Whisper.
• 2026-05-12 — DALL·E 2 / DALL·E 3 deprecated and removed from the API; Realtime API Beta deprecated and removed.
  • Impact: image generation migrates to GPT Image 2 (released 2026-04-21); voice migrates to the GPT-Realtime-2.x family.
• 2026-05-28 — Released chat-latest snapshot.

2026-04

• 2026-04-21 — Released GPT Image 2.
  • Impact: current flagship image generation model; check Usage Policy before commercial use.
• 2026-04-24 — Released GPT-5.5 and GPT-5.5 Pro. "GPT-5.5 supports a 1M token context window."

2026-03

• 2026-03-03 — Released gpt-5.3-chat-latest.
• 2026-03-05 — Released GPT-5.4 and GPT-5.4 Pro.
• 2026-03-12 — Sora API gained character references; sora-2 / sora-2-pro now support 1080p at $0.70 per second.
• 2026-03-16 — Updated the gpt-5.3-chat-latest slug.
• 2026-03-17 — Released GPT-5.4 mini and GPT-5.4 nano.

2026-02

• 2026-02-03 — GPT-5.2 and GPT-5.2-Codex run about 40% faster.
• 2026-02-10 — Updated the gpt-5.2-chat-latest slug.
• 2026-02-23 — Released GPT-Realtime-1.5 and gpt-audio-1.5.
• 2026-02-24 — Released gpt-5.3-codex.

2026-01

• 2026-01-14 — Released gpt-5.2-codex.

2025 historical (retired)

• GPT-5 (2025-08): first GPT-5 release; superseded by GPT-5.6 family on 2026-07-09.
• OpenAI o3 / o3-pro (2025-06): reasoning lineup; later folded into the GPT-5.6 reasoning.effort continuum.
• GPT-4.5 (2025-03): research preview, retired.
• GPT-4o / o1 / o3 / GPT-4.1 (2024–2025): the multi-family layout that GPT-5.6 collapses.

One-line current state

Flagship family = GPT-5.6 (Sol / Terra / Luna, 2026-07-09); since 2026-09-09 the next-generation flagship GPT-6-Astra is selectable in the Codex picker and Amazon Bedrock (the bundled official migration guide confirms Responses API usage and maps Sol→Astra with Terra/Luna retained; no pricing figure as of 2026-09-15). Voice = GPT-Realtime-2.1 (2026-07-06). Images = GPT Image 2.5 (sunburst / flare, in the SDK since 2026-09-08; the previous GPT Image 2 (2026-04-21) remains on sale, not deprecated). DALL·E 2/3 and the Realtime API Beta were both removed on 2026-05-12.

How this is built: fetch developers.openai.com/api/docs/changelog → extract (date, quote) per entry → place in the matching month block. dataSourcedAt records the most recent fetch.