Is gpt-5.6 the same model as GPT-5.6 Sol?

The bare `gpt-5.6` alias routes to GPT-5.6 Sol, so in practice yes. Sending the suffixed id is the clearer choice in production, because it pins the tier you are paying for rather than following whatever the alias points at later.

What is the GPT-5.6 Sol context window?

1,050,000 tokens, with a maximum output of 128,000 tokens. Those limits are shared across the GPT-5.6 family, so the cheaper tiers read just as much — what this tier adds is reasoning depth, not capacity.

What reasoning effort levels does GPT-5.6 Sol accept?

Six: none, low, medium, high, xhigh and max. The family default is medium, so a request that omits the field is not using this tier at its best. OpenAI describes high for hard reasoning and complex debugging, xhigh for deep research and long asynchronous runs, and max for the most complex tasks of all.

Can I use Pro reasoning mode with GPT-5.6 Sol here?

Pro mode is a feature of OpenAI's Responses API, where reasoning mode and reasoning effort are independent settings. This endpoint is OpenAI-compatible Chat Completions, so effort is the lever available on GPT-5.6 Sol through it. OpenAI notes that its reasoning models work better on Responses while Chat Completions remains supported — the family's changelog lists both.

Does GPT-5.6 Sol read images?

Yes. Input is text and image, output is text. This generation accepts images at their original dimensions with original or automatic detail, so fine print survives the trip in.

What is the GPT-5.6 Sol knowledge cutoff?

OpenAI lists February 16, 2026 for the whole GPT-5.6 family. For anything newer, give GPT-5.6 Sol web search or supply the material in the request.

Is GPT-5.6 Sol free or paid?

Paid. Usage is billed pay-as-you-go in USD from your api.reapi.ai token balance, based on input, output, and any applicable cache-token rates. See the live per-1M-token rates in the pricing table on this page; failed requests are not charged.

Does GPT-5.6 Sol require a monthly subscription?

No. There is no monthly subscription. Add funds to your api.reapi.ai token balance and pay in USD only for the input, output, and any applicable cache tokens each request uses. The live per-1M-token rates are in the pricing table on this page.

How do I get a GPT-5.6 Sol API key?

Sign up at api.reapi.ai and create a key under API Keys, then pass it as a Bearer token in the Authorization header. Chat keys and their token balance are separate from the reapi.ai image and video gateway.

GPT-5.6 Sol — Frontier Tier, 1.05M Context, Max Effort

GPT-5.6 Sol is the frontier model of the GPT-5.6 family and what the bare `gpt-5.6` alias resolves to. GPT-5.6 Sol reads a 1,050,000-token context window, returns up to 128,000 tokens, and carries the family's full six-rung reasoning ladder including the new max setting. OpenAI rates its reasoning Highest and its speed Fast. On reAPI, GPT-5.6 Sol bills 20% below OpenAI's published rate on both input and output.

GPT-5.6 Solmodelgpt-5.6-sol

GPT-5.6 Sol playground

Chat models run on the api.reapi.ai gateway, which has its own console and its own key. Open the console to run GPT-5.6 Sol through the OpenAI-compatible Chat Completions surface.

Open console Token rates

What is the GPT-5.6 Sol API?

GPT-5.6 Sol is the frontier tier of OpenAI's GPT-5.6 family and what the bare gpt-5.6 alias resolves to, served on reAPI through an OpenAI-compatible /v1/chat/completions endpoint. It reads a 1,050,000-token context window, returns up to 128,000 tokens, and carries the family's full six-rung reasoning ladder including the new max setting, with OpenAI rating its reasoning Highest and its speed Fast. Billing is per 1M tokens, with input and output priced separately; reasoning tokens count as output.

What you can build with this model

Real-world workflows and production use cases you can build and ship with this model.

GPT-5.6 Sol tracing a defect through a whole service before proposing a fix

The debugging and review work that has to be right

OpenAI's guidance for the top of the effort ladder names security and code review, complex debugging and deep planning — tasks where quality matters more than latency. GPT-5.6 Sol is the tier those settings were built for, and the shape of the work follows from the limits: a 1,050,000-token window means the service, its tests and its recent history all go into one request, so the model is reasoning about the actual system rather than a summary of it. Ask GPT-5.6 Sol to prove a cause before proposing a fix and the deep pass earns its cost; ask it to guess quickly and you are paying frontier rates for a cheap tier's job.

Read the API docs

GPT-5.6 Sol running a long multi-tool agentic task

Long-horizon agentic runs that do not drift

Deep research, asynchronous workflows and agentic tasks that require long runs are OpenAI's stated cases for xhigh, and this generation adds the pieces those runs need: programmatic tool calling, explicit prompt-caching controls and persisted reasoning. With functions, web search, file search and computer use all available, GPT-5.6 Sol is the tier you point at a task that will take many steps and many tool calls, where the failure you are buying protection against is not a wrong token but a plan that quietly falls apart at step thirty.

GPT-5.6 Sol weighing a high-stakes decision with full evidence in context

High-value judgement, where the cheap tier is the expensive choice

There is a class of request where a wrong answer costs more than the whole month's inference bill: a migration plan, a contract review, an architectural commitment, a security finding. On those, tier selection is not a cost decision. GPT-5.6 Sol is the model OpenAI puts at the top of this family — reasoning rated Highest, and the target of the bare `gpt-5.6` alias, which is a fair signal of where OpenAI expects the default to sit. Route the volume to a cheaper sibling and keep GPT-5.6 Sol for the calls you would want a senior engineer to make.

Pricing

Credit-based — 1 credit = $0.001 USD. Pay only for completed generations.

First test cost

$44,000 credits

One sample at the cheapest tier (1M tokens).

Testing budget guide

Add credits

$10

≈ 2 tests

$50

≈ 12 tests

$100

≈ 25 tests

Model	Category	Price
Token pricing	Input	$4 1M tokens
Token pricing	Output	$24 1M tokens

Why reAPI

20% below the published rate

OpenAI publishes a per-million-token rate for GPT-5.6 Sol input and output. On reAPI, GPT-5.6 Sol bills 20% below both — the same discount on each dimension, so an existing cost model scales down by a single figure. No subscription underneath it, no minimum commitment, pay-as-you-go in USD against your gateway balance. The exact numbers are in the pricing table on this page.

OpenAI-compatible drop-in

GPT-5.6 Sol is served from a standard `/v1/chat/completions` endpoint. If your code already speaks that shape, adopting GPT-5.6 Sol is a base URL, a key and a model string — the same SDKs work once the base URL points at the gateway. No SDK swap, no bespoke client.

One key across the whole ladder

The same api.reapi.ai key that calls GPT-5.6 Sol calls its cheaper siblings, the Claude and Gemini families, and the open-weight tiers. That is what makes a frontier tier affordable in practice: send the routine turns somewhere cheap and escalate to GPT-5.6 Sol by changing a model string, not by signing up with a second vendor.

GPT-5.6 Sol vs Claude Opus 5

Two frontier tiers, the same order of magnitude on price, and genuinely different contracts. GPT-5.6 Sol gives you a six-rung effort ladder that includes turning reasoning off entirely, image input, and a million-token window with a 128K output ceiling. Claude Opus 5 reasons by default, refuses the sampling parameters outright, and takes PDF rather than images. Neither is the general answer; the rows below are the ones that decide it for a given route.

Capability

GPT-5.6 Sol on reAPI

Claude Opus 5

Vendor positioning

Frontier model for complex professional work; reasoning rated Highest in its family

For complex agentic coding and enterprise work

Context and output limits

1,050,000-token context, 128,000-token maximum output

1M-token context, 128k maximum output

Reasoning default

Effort defaults to medium, and none turns reasoning off entirely

Thinking on by default; can be disabled only at effort high or lower

Effort ladder

Six rungs — none, low, medium, high, xhigh, max

Five rungs from low through max, defaulting to high

Sampling parameters

Reasoning effort is the intended control on this family

Sampling parameters removed — sending them returns an error

Non-text input

Images, at their original dimensions

Images and PDF

Comparison reflects behavior documented by each vendor at the time of writing. Rates are described as relationships rather than amounts; the live numbers for GPT-5.6 Sol are in the pricing table above.

Ship GPT-5.6 Sol in three steps

step 01
Create an account and key on api.reapi.ai
Sign up at api.reapi.ai, open the console and generate an API key. That one key reaches GPT-5.6 Sol and every other model on the gateway, billed from a single balance.
Open
step 02
Point your client at the gateway
Set your base URL to api.reapi.ai and your key to the one you just created. Any client that already speaks OpenAI Chat Completions works unchanged — no SDK swap is needed to reach GPT-5.6 Sol.
Open
step 03
Send `gpt-5.6-sol` as the model
Set the model field to `gpt-5.6-sol` — with the dots — and post your messages. Turn on streaming, since a deep pass can be slow to first token, and set reasoning effort deliberately: the family default is medium, and this tier is worth paying for at high and above.
Open

docs/api/gpt-5-6-sol

API reference

Drop-in code and the full parameter table.

View full reference

curl https://api.reapi.ai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.6-sol",
    "group": "default",
    "messages": [
      { "role": "user", "content": "Hello" }
    ],
    "reasoning_effort": "high",
    "stream": true
  }'

Parameter validation failed

Rejected synchronously with the failing field named. Check enum values, ranges, and URL fields — nothing is charged.

Authentication or balance issue

401 means a missing or invalid Bearer key; 402 means the reserve exceeds your balance. Manage keys and credits in the console.

Content or material rejected

Reference material and outputs pass automated moderation. Rejected tasks fail with a clear error and a full refund.

Task failed or timed out

A task that reaches a failed state is never charged — the reserve refunds automatically. Keep the task id and retry when ready.

Frequently asked questions

Common questions about this model.

GPT-5.6 Sol is billed pay-as-you-go in USD per token against your api.reapi.ai balance, with separate input and output rates and no subscription. Both sit 20% below OpenAI's published per-token rate. Current numbers are in the pricing table on this page.

They are the two frontier tiers most likely to be weighed against each other on this platform, and they sit in the same rate band with GPT-5.6 Sol the dearer of the two. The practical differences are shape rather than capability class: GPT-5.6 Sol has a six-rung effort ladder including an off setting and takes images, while Opus 5 reasons by default with a five-rung ladder and takes PDF. The versus table on this page has the row-by-row detail.