Current Flagship Activefrontierllm Proprietary

GPT-5.5

by OpenAI· Released May 2025· Cutoff April 2025

GPT-5.5 is OpenAI's most advanced flagship language model, offering state-of-the-art reasoning, creativity, and instruction following. It builds on GPT-5 with enhanced efficiency, lower latency, and improved performance across coding, analysis, and multimodal tasks. As the primary model in OpenAI's lineup, it powers ChatGPT and the API with superior accuracy and speed.

Official Site API Docs

Input cost

$2.50 per 1M tokens

Output cost

$10.00 per 1M tokens

Context window

256K tokens

Max output

16384 tokens

Modalities

textimage

License

proprietary

Capabilities

Function CallingVisionCode GenerationStreamingJSON ModeStructured OutputsParallel Tool CallsSystem Message Support

Best For

Complex reasoning, long-form content generation, advanced coding, and enterprise-grade applications requiring high accuracy and reliability.

Strengths

Superior reasoning and problem-solving across domains
Very low latency for a frontier model
Excellent instruction following and safety alignment
Strong performance on coding and math benchmarks

Limitations

Higher cost compared to smaller models
Not open source; proprietary
May still produce occasional hallucinations
Requires careful prompt engineering for optimal results

Use Cases

Advanced chatbot and virtual assistant

Complex code generation and debugging

Data analysis and report generation

Creative writing and content creation

Research assistance and summarization

Multilingual translation and localization

Enterprise workflow automation

Improvements Over Previous Model

Context window increased from 128K to 256K tokens
Output token limit doubled from 8192 to 16384
Pricing reduced: input $2.50/M vs $5.00/M, output $10.00/M vs $15.00/M
Latency reduced by approximately 40% compared to GPT-5
Improved coding benchmark scores (HumanEval 94% vs 90%)
Enhanced vision capabilities with better image understanding
Stronger instruction following and reduced refusal rates
Improved multilingual performance across 50+ languages

Back to all models

Improvements Over Previous Model

Context window increased from 128K to 256K tokens

Output token limit doubled from 8192 to 16384

Pricing reduced: input $2.50/M vs $5.00/M, output $10.00/M vs $15.00/M

Latency reduced by approximately 40% compared to GPT-5

Improved coding benchmark scores (HumanEval 94% vs 90%)

Enhanced vision capabilities with better image understanding

Stronger instruction following and reduced refusal rates

Improved multilingual performance across 50+ languages