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GPT-5.4 Pro API: Endpoint & Pricing

GPT-5.4 Pro is an OpenAI language model whose specific architecture, capabilities, and release details have not been publicly documented as of now.

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What is GPT-5.4 Pro?

GPT-5.4 Pro is a named OpenAI model for which no authoritative public technical description currently exists. It would likely be used for general-purpose natural language understanding and generation if officially released, but such use cases have not been formally described. It might also be positioned for advanced assistant, coding, or analysis tasks, yet these roles are not confirmed. It would presumably belong to the broader GPT family of large language models from OpenAI, though its exact place in that lineage has not been publicly defined.

Can you self-host GPT-5.4 Pro?

No. We found no public weights for GPT-5.4 Pro on Hugging Face, so there is nothing to download, quantize or serve on your own GPUs: no VRAM budget, no vLLM or GGUF build to plan for. The only way to run it is over an API.

Skip the deploy — use LLM.API as your endpoint

No GPUs, no quantization trade-offs. Same model, OpenAI-compatible, up to 30% below list price.

Get API keySee API code ↓

Providers

Different companies host the same model. OpenRouter routes your request to one of them based on the routing mode you pick — Balanced (price + speed), Nitro (fastest), or Exacto (highest tool-calling accuracy).

List price by provider

InputOutput
azure$30 in
$180 out
openai$30 in
$180 out

Provider list prices; the LLM.API discount applies on top.

Provider Input Output Cache read /M Latency Throughput Uptime
azurein $30; out $180 per 1M tokens1.1M tokensvision, tools, streaming, reasoning, web search, JSON, structured
openaiin $30; out $180 per 1M tokens1.1M tokensvision, tools, streaming, reasoning, web search, JSON, structured

Prices and availability from the LLMAPI catalogue, updated nightly. Last updated 8 Oct 2026.

Try this model

Test GPT-5.4 Pro right here — free to start.

GPT-5.4 Pro
Hi! Want to test the model?

Suggestions for your first prompt

Code snippet

Call the model through the OpenAI-compatible API.

Switching from OpenAI? Change 2 lines.

- base_url="https://api.openai.com/v1"
- api_key="YOUR_OPENAI_KEY"
+ base_url="https://api.llmapi.ai/v1"
+ api_key="YOUR_LLMAPI_KEY"

Everything else stays the same — SDK, message format, tools, streaming. Set model to gpt-5.4-pro and the call runs unchanged.

bash
curl https://api.llmapi.ai/v1/chat/completions \
  -H "Authorization: Bearer $LLMAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.4-pro",
    "messages": [
      {"role": "user", "content": "Give me three crisp launch checklist items."}
    ],
  "reasoning_effort": "none"
  }'
from openai import OpenAI

client = OpenAI(
    api_key="YOUR_LLMAPI_KEY",
    base_url="https://api.llmapi.ai/v1",
)

resp = client.chat.completions.create(
    model="gpt-5.4-pro",
    messages=[
        {"role": "system", "content": "You are a precise product assistant."},
        {"role": "user", "content": "Give me three crisp launch checklist items."},
    ],
    reasoning_effort="none",
)
print(resp.choices[0].message.content)
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.LLMAPI_KEY,
  baseURL: "https://api.llmapi.ai/v1",
});

const resp = await client.chat.completions.create({
  model: "gpt-5.4-pro",
  messages: [
    { role: "user", content: "Give me three crisp launch checklist items." },
  ],
});

console.log(resp.choices[0].message.content);
stream = client.chat.completions.create(
    model="gpt-5.4-pro",
    messages=[{"role": "user", "content": "Write a haiku about latency."}],
    stream=True,
)

for chunk in stream:
    delta = chunk.choices[0].delta.content
    if delta:
        print(delta, end="", flush=True)
{
  "model": "gpt-5.4-pro",
  "messages": [
    {"role": "system", "content": "You are a precise product assistant."},
    {"role": "user", "content": "Give me three crisp launch checklist items."}
  ],
  "reasoning_effort": "none"
}

ENDPOINTS

Supported endpoints & features

Base URL https://api.llmapi.ai/v1 · model ID gpt-5.4-pro · OpenAI-compatible.

  • POST /v1/chat/completionsChat Completions — supported
FeatureStatusHow to set it
Function calling (tools)Supportedtools, tool_choice
Parallel tool callsNot supportedparallel_tool_calls
JSON modeSupportedresponse_format: {"type": "json_object"}
Structured outputsSupportedresponse_format: {"type": "json_schema", …}
StreamingSupportedstream: true
Vision (image input)Supportedimage_url content parts
Web searchSupportedweb_search
Reasoning effortnone · low · medium · high · xhighreasoning_effort: "none"

ERRORS

Errors & fallback routing

CodeWhat it meansWhat to do
401Missing or invalid API key.Send Authorization: Bearer YOUR_LLMAPI_KEY and check the key is active.
429Rate limited, or the upstream provider is throttling the request.Back off and retry with jitter; the gateway also retries the request on another provider where one is available.
5xxUpstream provider error or timeout.Retry; fallback routing sends the retry to the next healthy provider for this model.

When a provider fails or throttles, the request is routed to the next provider serving this model — the ones listed in the providers table above.

Uptime

30-Day Uptime
96.70%
Past Incidents (30d)
3
Error rate (24h)
9.27%

Last 30 days

26/30 days operational | 96.70% uptime

30 days ago Today
Operational Degraded Outage Maintenance
See All Incidents

GPT-5.4 Pro in production

What the model is good at.

  • Advanced Chat

    Engages in multi-turn, context-aware conversations, following complex instructions and maintaining coherent dialogue across long interactions.

  • Multilingual Translation

    Translates between many languages while preserving meaning, tone, and style, supporting both casual text and more formal content.

  • Visual Understanding

    Interprets uploaded images to identify objects, infer relationships, and answer questions about visual content and layouts.

  • Document OCR

    Extracts machine-readable text from photographs or scans of documents, enabling downstream search, editing, and analysis workflows.

  • Usage Monitoring

    Supports integration into monitored environments, enabling logging of requests, responses, and performance metrics for deployed applications.

What you get when you call GPT-5.4 Pro through LLM.API.

  • Intelligent AI Routing

    Dynamically route each request to the optimal model across providers based on latency, cost, or quality policies—no client changes required.

    One endpoint, any model

  • Cost-Aware Orchestration

    Enforce budget policies, automatically choose cheaper equivalent models, and get transparent per-request cost estimates so teams can ship fast without surprise bills.

    Ship faster, spend less

  • Resilient Fallback Flows

    Design multi-provider fallback chains so timeouts or provider outages degrade gracefully instead of breaking your product or SLAs.

    No single point of failure

  • End-to-End Observability

    Trace every call across providers with logs, metrics, and structured events to debug prompts, compare models, and monitor production behavior in real time.

    See every token, everywhere

  • Task-Level Abstractions

    Target tasks like chat, generation, tools, or embeddings instead of vendor-specific APIs, simplifying integrations and making future provider swaps trivial.

    Code to tasks, not vendors

  • High-Throughput Batch APIs

    Submit large batches of requests in a single call to maximize throughput, reduce overhead, and keep costs predictable for bulk workloads.

    Bulk workloads, single call

When to Use — When NOT to Use

Use it if...

  • You need a strong general-purpose model for coding assistance, debugging, and refactoring.
  • You need advanced natural language understanding for chatbots, agents, and virtual assistants.
  • Your use case involves generating, editing, or summarizing long-form technical and business documents.
  • Your use case involves complex data analysis, SQL generation, and dashboard or report drafting.
  • You need a reliable model for multi-language translation, localization, and terminology standardization.
  • Your use case involves prototyping AI features quickly using a widely supported OpenAI model.

Avoid if...

  • You need the absolute cheapest possible model for simple classification or intent detection.
  • Your workload requires strict on-prem deployment with no external API dependencies whatsoever.
  • You need guaranteed fixed latency and throughput under highly constrained real-time conditions.
  • Your workload requires training or fine-tuning the base model entirely on your own infrastructure.
  • You need a highly specialized domain model already optimized on niche proprietary datasets.
  • Your workload requires offline inference on edge devices without stable internet connectivity.

LLM API rating for GPT-5.4 Pro

★ 3.0/ 5.0LLM API rating
50% production adoption · 30% category benchmark · 20% tooling & valueEstimated from published specs
2.5Production adoptionNot yet tracked — no public usage data for this release
3.5Benchmark qualityNo public Arena rank — scored on declared reasoning support
3.3Developer ecosystemContext window, tool and JSON support, price against the category median
Reasoning & chat 3.0Coding 3.4Vision & multimodal 3.0Tool & function calling 3.4Long context 3.4
How is this rating calculated?

Every model gets a separate 1.0–5.0 score for each category it can be used in, so a model can rate high for coding and lower for vision. The score combines three parts:

  1. Production adoption — 50%. How widely the model is actually used in production: provider traffic, LiteLLM and gateway usage, open-weight downloads and its LMArena rank. Proven, widely used models score highest.
  2. Category benchmark — 30%. The public benchmark that matters for that category — the Artificial Analysis Intelligence Index and LMArena Elo for reasoning, LMArena coding Elo for coding, image and document support plus vision Elo for vision, tool and JSON support for function calling, measured speed for voice.
  3. Tooling & value — 20%. Context window, support for tools, structured outputs and streaming, and price compared with the category median.

Scores of 4.0 and above are shown in green, 3.0–3.9 in yellow, below 3.0 in red. When a model has no public data for a part, it gets a neutral value instead of an invented number.

A “Verified benchmark” mark (✓) means an independent lab — LMArena or Artificial Analysis — has actually tested that model, and the source figure is shown. Models without that mark are labelled “Estimated from published specs”: the score comes from the published context window, tool and schema support, price and adoption only, because no independent lab has tested them yet.

One exception: a brand-new top-tier model that scores very high on the independent benchmarks but has no usage history yet is rated on the benchmark (60%) and tooling & value (40%) alone, so a missing adoption figure can't hold it back. All inputs come from public sources and are refreshed weekly.

Adoption and benchmark inputs come from public sources — LMArena, Artificial Analysis Intelligence Index and published model specs. Updated weekly.

COMMUNITY

What developers say about GPT-5.4 Pro

LMArena—Speed—Sources: LMArena, Artificial Analysis

Summarised from public developer discussions and write-ups. Opinions are the sources’, not LLM.API’s.

  • Developers on Hacker News report that GPT-5.4 Pro offers a 1M token context window, though some express skepticism regarding material performance gains when the context is mostly full.
  • Developers on LessWrong and personal blogs observe that GPT-5.4 Pro is the strongest compromise-free model available, showing significant improvements in long-horizon deliverables like financial models and complex coding tasks.
  • Developers on Hacker News note that despite the high context limit, prompts exceeding 272K input tokens incur a 2x pricing premium, making it significantly more expensive than standard tiers.

SOURCES

Frequently Asked Questions

  • What is GPT-5.4 Pro?

    GPT-5.4 Pro is a flagship OpenAI large language model exposed via LLM.API, optimized for high-quality reasoning, coding, and multi-step tool-using workflows.

  • What is GPT-5.4 Pro best suited for?

    GPT-5.4 Pro is best for complex application backends, advanced agents, long-form content generation, and code-heavy workloads requiring strong reasoning and reliability.

  • What is the context window of GPT-5.4 Pro?

    GPT-5.4 Pro supports a large context window suitable for long conversations, multi-file codebases, and extensive documents without frequent truncation.

  • How fast is GPT-5.4 Pro in typical LLM.API requests?

    On LLM.API, GPT-5.4 Pro is optimized for low p95 latency, providing interactive responses suitable for production user-facing applications.

  • What modalities does GPT-5.4 Pro support through LLM.API?

    Through LLM.API, GPT-5.4 Pro supports text input and output, and may also support additional modalities depending on LLM.API’s configured capabilities.

  • How is GPT-5.4 Pro priced on LLM.API?

    GPT-5.4 Pro pricing on LLM.API is usage-based per input and output token, with exact rates defined in your LLM.API billing and pricing documentation.

  • How do I call GPT-5.4 Pro via the LLM.API?

    You call GPT-5.4 Pro by specifying its model name in your LLM.API request payload, using the standard chat or completion endpoint.

  • How does GPT-5.4 Pro compare to other OpenAI models on LLM.API?

    GPT-5.4 Pro generally offers stronger reasoning and reliability than lighter OpenAI models, at a higher cost but better performance for demanding workloads.

  • Does GPT-5.4 Pro have any important limitations?

    GPT-5.4 Pro can still hallucinate, lacks real-time awareness, and must not be used as the sole source for high-stakes medical, legal, or financial decisions.

  • Can GPT-5.4 Pro use tools or structured function calling through LLM.API?

    Yes, GPT-5.4 Pro can be configured with tool or function calling on LLM.API to interact with external APIs, databases, and other services.

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    • Get one key to every model

    Swap your API key. Keep your code.

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