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Deep Dive

GPT-5: Everything Developers Need to Know

OpenAI's GPT-5 is here. We break down the new capabilities, benchmark results, API changes, and what it means for AI-powered development workflows.

Leanne ThuongJan 28, 202612 min read

GPT-5 represents a massive leap in AI capability. With improved reasoning, native tool use, and a 1M token context window, it changes the game for developers.

Key Improvements

The model brings significant advances in code generation accuracy, multi-step reasoning, and instruction following. Benchmarks show a 40% improvement over GPT-4o on complex coding tasks.

API Changes

The API now supports streaming tool calls, structured outputs with guaranteed schema compliance, and native image generation. The new `/v1/responses` endpoint replaces the old completions API.

What This Means for Developers

With GPT-5, many tasks that previously required fine-tuning now work out of the box. The improved function calling makes building AI agents significantly more reliable.

Pricing

Input tokens are $2.50/1M and output tokens are $10/1M -- roughly 50% cheaper than GPT-4o for equivalent quality. The mini version is even more affordable at $0.40/1M input.