GPT

GPT-4o (May 2024) was OpenAI's first natively multimodal model — text, audio and image in a single model, with a real-time voice mode and substantially lower cost than GPT-4 Turbo.

GPT-4o mini (July 2024) is OpenAI's small, low-cost variant of GPT-4o — positioned as the successor to GPT-3.5 Turbo, clearly stronger at a much lower price per token.

GPT-5.2 is OpenAI's model generation from December 2025 — three variants (instant, thinking, Pro), a 400k context window and new state-of-the-art on professional knowledge work.

GPT-5.3 is an iteration of OpenAI's GPT-5 line — the Instant variant launched on March 3, 2026 with a focus on factual accuracy, shorter preambles and a more natural conversational flow.

GPT-5.3-Codex is OpenAI's specialized agentic coding model (February 2026), the successor to GPT-5.2-Codex — 25% faster, with substantial gains on Terminal-Bench and OSWorld.

GPT-5.3-Codex-Spark is OpenAI's coding model from February 2026 — a smaller, real-time-optimized variant of GPT-5.3-Codex delivering over 1000 tokens per second on Cerebras hardware.

GPT-5.4 is OpenAI's reasoning model from March 5, 2026 — the first mainline model with the coding capabilities of GPT-5.3-codex, native computer-use controls and 1M-token context.

GPT-5.5 is OpenAI's flagship from April 23, 2026 — positioned as its "smartest and most intuitive model" and pitched as a step toward AI that works across tools on its own.