ProvenModels & PlatformsNew entryMarch 2026

Battle-tested in production. Build on it with confidence.

GPT-5 Family

GPT-5 replaces GPT-4.1 on the radar — the tiered family (Instant, Codex, Thinking, Pro) gives teams purpose-built models instead of one-size-fits-all.

LLM·Agentic

openai.com

Our Take

What It Is

The GPT-5 family is OpenAI's current generation of models, replacing the retired GPT-4.1 series. It's structured as a tiered family: GPT-5.3 Instant for fast everyday tasks, GPT-5.3-Codex ($1.75/$14 per million tokens) optimised for coding with 25% faster performance, GPT-5.4 Thinking for extended reasoning, and GPT-5.4 Pro for maximum capability. OpenAI also released GPT open-source models on HuggingFace, marking their first open-weight offering.

Why It Matters

GPT-5 enters the radar at Proven because it replaces a Proven model (GPT-4.1) and OpenAI's models remain foundational to the ecosystem. The tiered structure is the interesting evolution: instead of one model at one price, teams can route tasks to purpose-built variants. Simple classification goes to Instant, code generation to Codex, complex analysis to Thinking. This mirrors the Plan-and-Execute pattern we see emerging across the industry.

GPT-5.3-Codex at $1.75/$14 per million tokens makes it the cheapest frontier-quality coding model available. For teams running high-volume code generation workloads, the cost difference against Claude Opus ($5/$25) is significant. The quality-per-dollar equation continues to shift in practitioners' favour.

Key Developments

  • Mar 2026: GPT-5.1 models retired. GPT-5.4 family (Instant, Thinking, Pro tiers) announced.
  • Mar 2026: GPT-5.3 Instant released for fast everyday tasks at competitive pricing.
  • Feb 2026: GPT-5.3-Codex released — 25% faster coding with frontier quality at $1.75/$14 per million tokens.
  • Feb 2026: GPT-4.1 officially retired from ChatGPT. GPT open-source models released on HuggingFace.

What to Watch

The three-way frontier race between GPT-5.4 Pro, Claude Opus 4.6, and Gemini 3.1 Pro is the benchmark to track. Coding tasks and complex reasoning are where the models differentiate most. Watch for whether GPT-5.4 Thinking's extended reasoning capabilities match or exceed Claude's approach. The open-source GPT models on HuggingFace are worth monitoring — if OpenAI commits to open weights for production-ready models, it changes the competitive dynamics significantly.

Strengths

  • Tiered architecture: Purpose-built models (Instant, Codex, Thinking, Pro) let teams match capability to task requirements and budget.
  • Coding cost-performance: GPT-5.3-Codex at $1.75/$14 per million tokens is the most cost-effective frontier coding model available.
  • Ecosystem breadth: Largest third-party integration ecosystem of any model provider. Most AI tools support GPT models first.
  • Open-source entry: GPT models on HuggingFace signal a new direction for OpenAI and give teams open-weight options within the GPT family.

Considerations

  • Rapid deprecation: OpenAI retires model versions aggressively. GPT-4.1 retired within months of GPT-5 launch. Plan for migration.
  • Pricing complexity: Multiple model tiers with different pricing makes cost forecasting harder than single-model providers.
  • Safety approach: OpenAI's safety philosophy differs from Anthropic's Constitutional AI approach. Depending on your requirements, this may be a factor.
  • API changes: OpenAI's API has evolved significantly across generations. Major version upgrades often require code changes.