OpenAI 2026 H2 Model and API Release Timeline

This timeline is a living reference, synced every two weeks with the official changelog. New entries prepended with date.

2026-07

2026-07-09 · GPT-5.6 Family Release · Impact: High

OpenAI released the GPT-5.6 family on 2026-07-09, three tiers:

• Sol (gpt-5.6-sol, alias gpt-5.6): $5/$30 per MTok, flagship / Frontier
• Terra (gpt-5.6-terra): $2.50/$15 per MTok, daily workhorse
• Luna (gpt-5.6-luna): $1/$6 per MTok, high-throughput batch

All three share 1.05M context, 128K output, knowledge cutoff 2026-02-16, native multimodal input. Depth is controlled continuously by reasoning.effort (none / low / medium / high / xhigh / max).

Developer impact: H1 had multiple coexisting models (GPT-4o / o1 / o3 / GPT-4.1 / GPT-5.5, etc.); now converged to 3 tiers. You need to:

• Replace model="gpt-4o" with model="gpt-5.6-terra" (the closest old tier)
• Replace model="o1" with model="gpt-5.6-sol" + reasoning={"effort": "high"}
• Re-evaluate token costs: Sol costs ~3× GPT-4o but produces higher quality; recommend Terra + Luna for primary, Sol for critical paths
• Chat Completions API is marked legacy; new projects should use the Responses API (input field)

2026-07-06 · GPT-Realtime-2.1 Release · Impact: High

OpenAI released GPT-Realtime-2.1 on 2026-07-06 — current flagship Realtime model, the base for ChatGPT Advanced Voice.

Developer impact: Realtime API projects upgrade to 2.1, model id becomes gpt-realtime-2.1. WebRTC ephemeral token endpoint changes to POST /v1/realtime/client_secrets (response field is value), and the browser exchanges SDP via POST /v1/realtime/calls.

2026-08

2026-08-26 · Assistants API shut down + transcription deprecations · Impact: High

Per the official changelog: the Assistants API shut down on 2026-08-26; migrate to the Responses API / Conversations API (official migration guide available). The same day, four transcription models were deprecated -- whisper-1, gpt-4o-transcribe, gpt-4o-mini-transcribe, and gpt-4o-transcribe-diarize -- shutting down on 2027-02-26; migrate to gpt-live-transcribe / gpt-transcribe.

2026-08-21 · GPT-5.6 Sol price cut (promo) · Impact: High

Per the official changelog: Sol drops to $4/$20 per MTok (input -20%, output -33%), with promo pricing lasting at least through 2026-11-21; previously $5/$30. Same day: API customers can select per-request regional processing (prefixed domain with a Global-geography project key).

2026-08-07 · GPTMap Editorial Update · Impact: Low

As of 2026-08-07, GPTMap had 24 articles (48 bilingual files), covering 14 channels with distribution: 6 channels at 2 articles, 4 channels at 1 article. H2 plan: 4-6 articles per month, prioritizing gap channels.

This is a GPTMap-internal note, not an OpenAI release.

2026-09

Officially confirmed September milestones (verified against the official deprecations page on 2026-09-01).

2026-09-24 · Sora 2 and Videos API shutdown · Impact: high

Official deprecations batch of 2026-03-24: the Videos API, sora-2, sora-2-pro, sora-2-2025-10-06, sora-2-2025-12-08, and sora-2-pro-2025-10-06 all shut down on 9-24; the recommended-replacement column is empty -- no official replacement suggested.

2026-09-28 · completions-era legacy model shutdown · Impact: low

gpt-3.5-turbo-instruct, babbage-002, davinci-002, and gpt-3.5-turbo-1106 shut down; official replacement suggestion: gpt-5.6-terra.

Former predictions (GPT-5.6 fine-tuned variants, GPT Image 2.1) were never officially confirmed and have been removed from this timeline; they will be re-added if officially announced.

2026-Q4 (TBD)

• GPT-6 candidate (no official timeline, TBD): OpenAI's public line is that GPT-5.6 family continues iterating; no GPT-6 release date announced
• Realtime 3.x (TBD): further real-time performance improvements expected
• Azure OpenAI GA sync (TBD): Azure GA timing for GPT-5.6 and Realtime-2.1

H1 highlights (2026-01 to 2026-06)

Maintenance notes

This article follows the guides-article-maintenance flow:

• Re-scrape developers.openai.com/api/docs/changelog every two weeks
• Major events (model rename, pricing change, API field deprecation) trigger immediate re-test
• New entries prepended with date; older entries retained for timeline traceability

What's Next

• OpenAI Models Release Notes (2026, Living Document) — mirror-style changelog
• The GPTMap editorial checklist: 12 steps to a publishable OpenAI article
• GPTMap Article Maintenance Guide: Re-testing, Version Sync, and Sunset

Update log

• 2026-08-08: Initial publish (2026-07 events + 2026-08 internal + H1 retrospective table)