GPT-5.4
OpenAI's unified flagship combining GPT and o-series reasoning into one model. 1M context, multimodal, top SWE-Bench Pro and OSWorld scores.
GPT-5.4 is multimodal AI model from OpenAI, priced at €0.003 per 1M input tokens with a 1.1M tokens context window.
About this model
0.7
Pricing
API Integration
Use our OpenAI-compatible API to integrate GPT-5.4 into your application.
npm install railwailimport railwail from "railwail";
const rw = railwail("YOUR_API_KEY");
// Simple — just pass a string
const reply = await rw.run("gpt-5-4", "Hello! What can you do?");
console.log(reply);
// With message history
const reply2 = await rw.run("gpt-5-4", [
{ role: "system", content: "You are a helpful assistant." },
{ role: "user", content: "Explain quantum computing simply." },
]);
console.log(reply2);
// Full response with usage info
const res = await rw.chat("gpt-5-4", [
{ role: "user", content: "Hello!" },
], { temperature: 0.7, max_tokens: 500 });
console.log(res.choices[0].message.content);
console.log(res.usage);Deep dive — OpenAI's GPT-5.4
OpenAI was founded in December 2015 by Sam Altman, Elon Musk, Greg Brockman, Ilya Sutskever, Wojciech Zaremba and John Schulman as a non-profit AI research organisation; it transitioned to a 'capped-profit' structure in 2019. OpenAI authored the GPT lineage starting with GPT-1 (2018), GPT-2 (2019), GPT-3 (2020), the ChatGPT launch with GPT-3.5 (November 2022), GPT-4 (March 2023), GPT-4o (May 2024), the o-series reasoning models o1 (December 2024) and o3 (early 2025), then GPT-5 (mid-2025). The GPT-5.x series unified the reasoning o-series with the general-purpose GPT line: GPT-5.2 shipped December 2025, GPT-5.3-Codex February 2026, GPT-5.4 in March 2026 and the GPT-5.5 family later in 2026. OpenAI's investors include Microsoft (~$13B+), Khosla Ventures, Andreessen Horowitz, Thrive Capital and Sequoia, with total funding exceeding $60 billion and a 2026 valuation above $300 billion.
Visit OpenAI →GPT-5.4 is OpenAI's frontier model as of March 2026 and marks the full convergence of the previously separate o-series reasoning models and general-purpose GPT line into a single unified architecture. The o1, o3, o3-pro and o4-mini reasoning models were retired from ChatGPT on February 13, 2026; their capabilities are now folded into GPT-5.x as a 'Thinking' tier that activates on demand. GPT-5.4 also absorbs the Codex line for agentic coding. Pretraining used a multi-trillion-token mixture of web text, code repositories, scientific papers, books and licensed datasets on OpenAI's most recent supercomputer cluster. Post-training combined supervised fine-tuning, RLHF and large-scale reinforcement learning against verifiable rewards on coding, math and tool-use trajectories. The model supports native text + image input and a 1.05M-token experimental context window (272K standard), 128K max output, integrated tool-use, function calling, structured outputs, and built-in 'Tool Search' for delegating to subagents. Safety training followed OpenAI's Preparedness Framework with red-teaming, capability evaluations and external assessments.
- Parameters
- Undisclosed (estimated multi-hundred billion parameters, likely sparse MoE)
- Context
- 1.1M tokens
- Unified GPT and o-series: integrated 'Thinking' tier activates on demand
- 1.05M-token experimental context window (272K standard, 128K max output)
- Native multimodal input: text and images in a single pass
- Top scores on SWE-Bench Pro and OSWorld-Verified at launch
- Native tool use, function calling, parallel tool calls and structured outputs
- Integrated 'Tool Search' for delegating to subagent models
- Absorbed Codex agentic coding capabilities
- Strong multilingual performance and instruction following
- Available via OpenAI API, Azure OpenAI, ChatGPT and Codex CLI
- Regional processing (data residency) endpoints available with 10% uplift
- Best for: high-context coding, agentic engineering, multimodal analysis, complex tool-use workflows.
Pretrained on a multi-trillion-token mixture of web text, code, scientific papers, books and licensed datasets. Post-training combines supervised fine-tuning, RLHF and large-scale reinforcement learning against verifiable rewards on coding, math and tool-use tasks. Knowledge cutoff approximately late 2025.
License: Proprietary commercial license via OpenAI API and Azure OpenAI. Commercial use permitted under OpenAI's Usage Policies.
Known limitations
- 1M context is experimental and must be enabled explicitly (default is 272K)
- Prompts above 272K input tokens are billed at 2x input / 1.5x output for the full session
- No native audio or video input in this variant
- Higher latency and cost than mini/nano tiers, especially with Thinking enabled
- Knowledge cutoff in late 2025
Frequently asked questions
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