OpenAI
GPT-5.4
From $1.00 per 1M tokens
Chat
GPT-5.6 Luna — 1.05M Context at the Volume Tier
GPT-5.6 Luna is OpenAI's cost-sensitive tier of the GPT-5.6 family, and the interesting part is what it does not give up: GPT-5.6 Luna carries the same 1,050,000-token context window, the same 128,000-token maximum output and the same six-rung reasoning dial as its frontier sibling. What changes is the price and the depth of thinking you would sensibly ask of it. On reAPI, GPT-5.6 Luna bills 20% below OpenAI's published rate on both input and output.
GPT-5.6 Lunamodel
gpt-5.6-lunaGPT-5.6 Luna 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 Luna through the OpenAI-compatible Chat Completions surface.
What you can build with this model
Real-world workflows and production use cases you can build and ship with this model.
Classification and extraction, priced for the whole queue
This is the work OpenAI names for the lowest effort setting: fast information retrieval and classification, where reasoning adds latency and nothing else. Turn effort off, constrain the output with a schema, and GPT-5.6 Luna becomes a component rather than an oracle — the same prompt over a million rows, at a rate where the arithmetic still works. The part worth noticing is that dropping to this tier does not shrink your inputs: GPT-5.6 Luna reads the same 1,050,000-token window as the frontier tier, so a long document does not force you back up the price ladder just to fit.
Read the API docs
The cheap first pass in front of an expensive model
Most production traffic is not hard. A two-stage route built on GPT-5.6 Luna — it reads everything and decides what is routine, a dearer model sees only what is not — is the single most effective cost lever available on a chat workload, and it works precisely because the cheap stage here is not a weak model but a smaller tier of the same family with the same limits and the same interface. Same key, same endpoint, one model string apart: escalation is a field in your request, not a second integration.
Latency-critical paths where thinking is the wrong tool
Voice, autocomplete, live moderation, anything a human is waiting on: OpenAI's own advice for these is to try low effort first and move to none if required. GPT-5.6 Luna is the tier where that advice is cheapest to follow, and where the speed rating is Fast to begin with. Keep the prompt short, keep the output bounded, and treat effort as the dial you turn before you go looking for a different provider — the family's fast path and its deep path are the same API.
Pricing
Credit-based — 1 credit = $0.001 USD. Pay only for completed generations.
| Category | Unit | Price |
|---|---|---|
| Token pricing | ||
| Input | 1M tokens | $0.8 |
| Output | 1M tokens | $4.8 |
Why reAPI
20% below the published rate
OpenAI publishes a per-million-token rate for GPT-5.6 Luna input and output. On reAPI, GPT-5.6 Luna bills 20% below both — the same discount on each dimension, so your existing cost model scales down by one 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 Luna is served from a standard `/v1/chat/completions` endpoint. If your code already speaks that shape, adopting GPT-5.6 Luna 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 Luna calls its larger siblings, the Claude and Gemini families, and the open-weight tiers. That is what makes tiered routing practical: the escalation target is a model string, not a second vendor relationship with its own invoice and credentials.
GPT-5.6 Luna vs GPT-5.6 Terra
This is the comparison that actually decides a route, and it is unusually clean because GPT-5.6 Luna and GPT-5.6 Terra share almost everything: same context window, same output ceiling, same effort ladder, same tools, same knowledge cutoff, same endpoint. What differs is the reasoning headroom OpenAI rates each for, the lineage they descend from, and the price. Read the rows below as: does this route need judgement, or does it need throughput?
Capability
GPT-5.6 Luna on reAPI
GPT-5.6 Terra
OpenAI's positioning
Optimised for cost-sensitive, high-volume workloads
Balances intelligence and cost
Reasoning rating
High — the family's entry rating
Higher — one step up
Earlier-generation lineage
Corresponds to the nano tier of earlier GPT-5 families
Corresponds to the mini tier
Rate on reAPI
The lowest of the three tiers — see the pricing table above
Higher than Luna, lower than the frontier tier
Context and output limits
1,050,000-token context, 128,000-token maximum output
Identical — the limits do not change across tiers
Effort ladder and tools
All six rungs, functions, web search, file search, computer use
Identical — the difference is which rungs are worth paying for
Comparison reflects behavior documented on OpenAI's own model pages at the time of writing. Rates are described as relationships rather than amounts; the live numbers for GPT-5.6 Luna are in the pricing table above.
Ship GPT-5.6 Luna 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 Luna 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 Luna.
Open - step 03
Send `gpt-5.6-luna` as the model
Set the model field to `gpt-5.6-luna` — with the dots — and post your messages. On this tier, set reasoning effort deliberately: the family default is medium, and on high-volume routes none or low is usually what you actually want.
Open
Frequently asked questions
Common questions about this model.
GPT-5.6 Luna 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.
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