GPT 5.1 Chat Latest

The gpt-5.1 chat latest API serves the GPT-5.1 snapshot that ran inside ChatGPT, tuned for fast, natural conversation. With a 128K-token context window, text and image input, and native function calling, gpt 5.1 chat fits chatbots, support agents, and RAG. Generate one GPTProto gpt 5.1 chat api key and call it alongside gpt 5.5 and every other model from a single endpoint.

Modalities

API Usage Examples

curl --request POST "https://gptproto.com/v1/chat/completions" \
  --header "Authorization: Bearer $GPTPROTO_API_KEY" \
  --header "Content-Type: application/json" \
  --data '{
    "model": "gpt-5.1-chat-latest",
    "messages": [
      {
        "role": "user",
        "content": "Hello"
      }
    ]
  }'

GPT 5.1 Chat Latest pricing

Chat, coding agents & document work. Priced per 1M tokens — input, cached input and output are billed separately. GPTProto is 20% below official rates.

Your usage

Model

OpenAI · ≈ 148M tokens/mo (48M cached)

Monthly volume

OpenRouter

List + 5.5% credit fee

$259.53

per month

Input (non-cached)$42.20

Cache read$6.33

Output$211

OpenAI

Direct from OpenAI (list price)

$246

per month

Input (non-cached)$40

Cache read$6

Output$200

BEST VALUE

GPTProto

20% off official

$196.80

per month

After discount$196.80

Effective$196.80

Monthly cost by source

OpenRouter

$259.53

OpenAI

$246

GPTProto

$196.80

Save $49.20 / month

on GPTProto vs OpenAI (−20%)

Annual savings ≈ $590.40 · pay as you go

OpenRouter costs include its ~5.5% credit purchase fee. GPTProto applies a per-model discount (10–30% off) and your bonus credits are also spent at discounted rates — savings compound. Estimates assume a 60% cache hit rate.

Related Models

All Models

GPT 5.1 Chat Latest

Current

byOpenAI$1/M input$8/M output

DeepSeek Flash

byDeepSeek$0.3/M input$1.2/M output

Hy4 Preview

byHunyuan1.05M context$0.7923/M input$2.376/M output

GPT 6 Astra

byOpenAI1.05M context$8/M input$40/M output

Gemini 3.8 Flash

byGoogle1.05M context$0.9/M input$4.5/M output

Claude Fable 5.1

byClaude1M context$9/M input$45/M output

Qwen3.8 Max 0902

byQwen1M context$1.8/M input$5.4/M output

GLM 5.3 Flash

byZ-AI1.31M context$0.15/M input$0.5/M output

DeepSeek v4 Flash Vision Exp

byDeepSeek1.05M context$0.3/M input$1.2/M output

GLM 5.3

byZ-AI1.31M context$1.26/M input$3.96/M output

Gemini 3.7 Flash

byGoogle1.05M context$0.9/M input$4.5/M output

Grok 4.6

byGrok500K context$1.2/M input$3.6/M output

Qwen3.8 Max

byQwen1M context$1.8/M input$5.4/M output

Claude Opus 5

byClaude1M context$4.5/M input$22.5/M output

Gemini 3.6 Flash

byGoogle1.05M context$0.9/M input$4.5/M output

Kimi K3

byMoonshotAI1.05M context$2.7/M input$13.5/M output

GPT 5.6 Luna

byOpenAI1.05M context$0.16/M input$0.96/M output

GPT 5.6 Terra

byOpenAI1.05M context$1.6/M input$9.6/M output

GPT 5.6 Sol

byOpenAI1.05M context$3.2/M input$16/M output

Grok 4.5

byGrok500K context$1.2/M input$3.6/M output

Claude Sonnet 5

byClaude1M context$1.8/M input$9/M output

Minimax M3

byMiniMax1.05M context$0.48/M input$0.96/M output

GLM 5.2

byZ-AI1.05M context$1.26/M input$3.96/M output

Qwen3.7 Max

byQwen1M context$0.36/M input$1.44/M output

DeepSeek v4 Flash

byDeepSeek1.05M context$0.3/M input$1.2/M output

Grok 4.3

byGrok1M context$0.75/M input$1.5/M output

GPT 5.4 Pro

byOpenAI1.05M context$24/M input$144/M output

GPT 5.5 Pro

byOpenAI1.05M context$24/M input$144/M output

Kimi K2.6

byMoonshotAI262K context$0.855/M input$3.6/M output

Minimax M2.5

byMiniMax205K context$0.24/M input$0.96/M output

Kimi K2.5

byMoonshotAI262K context$0.54/M input$2.7/M output

Doubao Seed 1.6 Thinking (Build 250715)

byBytedance262K context$0.0971/M input$0.9714/M output

Doubao Seed 1.6 Thinking (Build 250615)

byBytedance262K context$0.0971/M input$0.9714/M output

Doubao Seed 1.6 Flash (Build 250615)

byBytedance262K context$0.0182/M input$0.1821/M output

Model					Input → Output
GPT 5.1 Chat LatestCurrent $		—	$1.00 / $8.00 per 1M	$0.10 / $0.10 per 1M	Input: TextInput: ImageInput: Document Output: Text
DeepSeek Flash $	—	—	$0.30 / $1.20 per 1M	— / $0.006 per 1M	Input: TextInput: Image Output: Text
Hy4 Preview $		1.05M	$0.79 / $2.38 per 1M	— / $0.04 per 1M	Input: Text Output: Text
GPT 6 Astra $		1.05M	$8.00 / $40.00 per 1M	$10.00 / $0.80 per 1M	Input: TextInput: ImageInput: Document Output: Text
Gemini 3.8 Flash $		1.05M	$0.90 / $4.50 per 1M	$0.60 / $0.09 per 1M	Input: TextInput: ImageInput: VideoInput: DocumentInput: Audio Output: Text
Claude Fable 5.1 $		1M	$9.00 / $45.00 per 1M	$11.25 / $0.23 per 1M	Input: TextInput: ImageInput: Document Output: Text
Qwen3.8 Max 0902 $		1M	$1.80 / $5.40 per 1M	$2.25 / $0.23 per 1M	Input: TextInput: ImageInput: VideoInput: DocumentInput: Audio Output: Text
GLM 5.3 Flash $	—	1.31M	$0.15 / $0.50 per 1M	— / $0.03 per 1M	Input: TextInput: ImageInput: VideoInput: Document Output: Text
DeepSeek v4 Flash Vision Exp $	—	1.05M	$0.30 / $1.20 per 1M	— / $0.006 per 1M	Input: TextInput: Image Output: Text
GLM 5.3 $		1.31M	$1.26 / $3.96 per 1M	— / $0.23 per 1M	Input: TextInput: ImageInput: Document Output: Text
Gemini 3.7 Flash $		1.05M	$0.90 / $4.50 per 1M	$0.60 / $0.09 per 1M	Input: TextInput: ImageInput: Document Output: Text
Grok 4.6 $		500K	$1.20 / $3.60 per 1M	— / $0.30 per 1M	Input: TextInput: Image Output: Text
Qwen3.8 Max $		1M	$1.80 / $5.40 per 1M	$2.25 / $0.23 per 1M	Input: TextInput: ImageInput: VideoInput: Document Output: Text
Claude Opus 5 $		1M	$4.50 / $22.50 per 1M	$5.63 / $0.45 per 1M	Input: TextInput: ImageInput: Document Output: Text
Gemini 3.6 Flash $		1.05M	$0.90 / $4.50 per 1M	$0.60 / $0.09 per 1M	Input: TextInput: ImageInput: Document Output: Text
Kimi K3 $		1.05M	$2.70 / $13.50 per 1M	$0.27 / $0.27 per 1M	Input: TextInput: ImageInput: Document Output: Text
GPT 5.6 Luna $		1.05M	$0.16 / $0.96 per 1M	$0.20 / $0.02 per 1M	Input: TextInput: ImageInput: Document Output: Text
GPT 5.6 Terra $		1.05M	$1.60 / $9.60 per 1M	$2.00 / $0.16 per 1M	Input: TextInput: ImageInput: Document Output: Text
GPT 5.6 Sol $		1.05M	$3.20 / $16.00 per 1M	$4.00 / $0.32 per 1M	Input: TextInput: ImageInput: Document Output: Text
Grok 4.5 $		500K	$1.20 / $3.60 per 1M	$0.30 / $0.30 per 1M	Input: TextInput: Image Output: Text
Claude Sonnet 5 $		1M	$1.80 / $9.00 per 1M	$2.25 / $0.18 per 1M	Input: TextInput: Document Output: Text
Minimax M3 $		1.05M	$0.48 / $0.96 per 1M	$0.10 / $0.10 per 1M	Input: TextInput: ImageInput: Document Output: Text
GLM 5.2 $		1.05M	$1.26 / $3.96 per 1M	$0.23 / $0.23 per 1M	Input: TextInput: ImageInput: Document Output: Text
Qwen3.7 Max $		1M	$0.36 / $1.44 per 1M	$0.07 / $0.07 per 1M	Input: TextInput: Document Output: Text
DeepSeek v4 Flash $	—	1.05M	$0.30 / $1.20 per 1M	— / $0.006 per 1M	Input: Text Output: Text
Grok 4.3 $		1M	$0.75 / $1.50 per 1M	$0.12 / $0.12 per 1M	Input: TextInput: Image Output: Text
GPT 5.4 Pro $		1.05M	$24.00 / $144.00 per 1M	—	Input: TextInput: ImageInput: Document Output: Text
GPT 5.5 Pro $		1.05M	$24.00 / $144.00 per 1M	—	Input: TextInput: ImageInput: Document Output: Text
Kimi K2.6 $		262K	$0.85 / $3.60 per 1M	$0.14 / $0.14 per 1M	Input: TextInput: Document Output: Text
Minimax M2.5 $		205K	$0.24 / $0.96 per 1M	$0.30 / $0.02 per 1M	Input: TextInput: Document Output: Text
Kimi K2.5 $		262K	$0.54 / $2.70 per 1M	$0.09 / $0.09 per 1M	Input: TextInput: Document Output: Text
Doubao Seed 1.6 Thinking (Build 250715) $		262K	$0.10 / $0.97 per 1M	—	Input: TextInput: Image Output: Text
Doubao Seed 1.6 Thinking (Build 250615) $		262K	$0.10 / $0.97 per 1M	—	Input: TextInput: Image Output: Text
Doubao Seed 1.6 Flash (Build 250615) $		262K	$0.02 / $0.18 per 1M	—	Input: TextInput: Image Output: Text

gpt-5.1 chat latest API

Verified specs, pricing, and how gpt 5.1 chat compares to gpt 5.1 and gpt 5.5 — one GPTProto key for all of them.

gpt 5.1 chat Adaptive Reasoning

gpt 5.1 chat carries the ChatGPT-tuned reasoning that improves accuracy on technical and math prompts over GPT-5.0. Need configurable reasoning_effort? Use the full gpt-5.1 model instead.

Agentic Tool Use

The gpt-5.1 chat latest API supports native function calling and structured JSON outputs, so your agents trigger tools and return clean, parseable results across multi-step workflows — no extra glue layer required.

128K Context Window

gpt 5.1 chat handles a 128K-token context window with up to 16K output tokens — enough for long conversations, document Q&A, and retrieval pipelines without mid-thread truncation.

Text + Image Vision

The gpt 5.1 chat api accepts text and image input in a single call for screenshot reading, chart parsing, and visual Q&A. Note: this model does not process video or audio.

What Is the gpt-5.1 chat latest API?

The gpt-5.1 chat latest API exposes the exact GPT-5.1 snapshot that powered ChatGPT, delivered through GPTProto's unified endpoint. Unlike the full gpt-5.1 reasoning model, the chat-latest alias is tuned for fast, conversational replies — a 128K context window, text-and-image input, streaming, and native function calling — which makes it a drop-in pick for chatbots, support flows, and lightweight RAG. One key reaches gpt 5.1 chat and every other model on the platform.

GPT-5.1 Chat latest vs GPT 5.1 vs GPT 5.5

	gpt-5.1 chat latest	gpt 5.1	gpt 5.5
Best for	Chat, support bots, light RAG	Agentic + coding, reasoning	Frontier reasoning, long-doc
Context window	128K	400K	1M
Max output	16K	128K	128K
Reasoning control	Chat-tuned (fixed)	`reasoning_effort` none–high	`reasoning_effort` none–xhigh
Input	Text + image	Text + image	Text + image
Video / audio	✗ / ✗	✗ / ✗	✗ / ✗
Knowledge cutoff	Sep 30 2024	Sep 30 2024	Dec 1 2025
Price (OpenAI list)	$1.25 / $10	$1.25 / $10	$5 / $30
Price on GPTProto	$1 / $8	$0.875 / $7	$4 / $24
Status	Deprecated snapshot	Current	Current flagship

gpt 5.1 chat latest vs gpt 5.1

The difference is snapshot vs base model. The full gpt-5.1 model ships a 400K context window and configurable reasoning_effort (none, low, medium, high) for agentic and coding work. The gpt-5.1 chat latest alias mirrors the ChatGPT chat experience: lower latency, a 128K window, and conversational tuning rather than long step-by-step reasoning. Choose the chat alias for dialogue; choose gpt 5.1 for tool-heavy autonomous tasks.

gpt-5.1 chat latest vs gpt 5.5

gpt 5.5 is OpenAI's current flagship — a 1M-token context window and stronger reasoning at a higher price. gpt 5.1 chat is cheaper and faster for everyday chat, but for long-document analysis or frontier accuracy, gpt 5.5 is the upgrade — available under the same GPTProto key, so migrating is a one-line model swap.

Is ChatGPT 5.1 being retired? Is it better than GPT-5.0?

Yes — OpenAI retired the GPT-5.1 family from ChatGPT on March 11, 2026, migrating conversations to newer 5.x models, and the gpt-5.1-chat-latest API snapshot is now marked deprecated. It stays reachable through GPTProto for teams that pinned to it. Versus GPT-5.0, gpt 5.1 chat brought a warmer tone and more reliable instruction-following; against the 5.5 line it now trails on context length and reasoning. Starting fresh? Build on gpt 5.5 and keep gpt 5.1 chat for parity testing or legacy compatibility.

At GPTProto, gpt-5.1 chat latest API pricing runs $1 / $8 per 1M input/output tokens — under OpenAI's $1.25 / $10 list — with one key spanning every model on the platform.

gpt 5.1 chat Frequently Asked Questions

Expert answers to common technical queries about gpt 5.1 chat integration and reasoning capabilities.

How does gpt 5.1 chat handle System 2 reasoning?

The gpt 5.1 chat model uses a native reasoning engine to verify its logic before outputting text. This process, controlled by the reasoning_effort parameter, allows the gpt to pause and 'think' through multi-step problems in math, physics, and code, resulting in 40% fewer logical fallacies compared to older gpt versions like 4o.

What is the context window for gpt 5.1 chat?

gpt 5.1 chat has a 128K-token context window with up to 16K output tokens — enough for long conversations, document Q&A, and RAG context in a single request. Cached input tokens are billed at a lower rate, so repeated system prompts stay cost-efficient across gpt 5.1 chat sessions. For 400K or 1M-token jobs, step up to gpt-5.1 or gpt 5.5.

Can gpt 5.1 chat process video files directly?

No. gpt 5.1 chat accepts text and image input only — video and audio are not supported on this model. You can pass screenshots, charts, and photos for visual Q&A, but for video you'll need to extract frames as images first, or use a dedicated video model on the platform.

How do I configure gpt 5.1 chat reasoning_effort?

The reasoning_effort parameter (none, low, medium, high) is configured on the gpt-5.1 model, not the chat-latest alias, which is tuned for fast conversation. To dial reasoning depth for coding or math, call gpt-5.1 and set reasoning_effort in your request; stay on gpt 5.1 chat when low-latency dialogue matters more than deep reasoning.

Is gpt 5.1 chat suitable for real-time voice apps?

While gpt 5.1 chat supports audio, its reasoning overhead creates latency that may exceed the sub-200ms requirements for fluid voice-to-voice bots. For those use cases, we recommend gpt 4o-Realtime, as gpt 5.1 chat is optimized for depth and accuracy rather than raw conversational speed.

Is my data used to train the gpt 5.1 chat model?

No. When using gpt 5.1 chat via GPTProto, your data is protected. Our platform and the underlying OpenAI API agreement strictly prohibit the use of customer inputs or outputs for training gpt foundation models, ensuring enterprise-grade privacy for all your gpt 5.1 chat projects.