AionLabs: Aion 3.5
Aion 3.5 is a reasoning model from AionLabs released on Sep 23, 2026. It reads text and writes text, with a 262K token context window and up to 33K tokens per reply.
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It costs $3 per million input tokens and $6 per million output tokens. Cached input bills at $0.75, 75% less than fresh input.
It supports tool calling and prompt caching.
2 providers serve it, including Kilo Gateway and NanoGPT.
- Modalities
- In / out price
- $3 / $6 per 1M
- Context
- 262K
- Max output
- 33K
- Released
- Sep 23, 2026
- Knowledge cutoff
- n/a
- Tool calling
- Structured output
- Reasoning
- Prompt caching
- Open weights
- Free to use
Aion 3.5 pricing
USD, as listed on Oct 15, 2026. Most bills are input heavy, so the cached input rate matters as much as the headline price.
| Input | $3 / 1M tokens | |
|---|---|---|
| Output | $6 / 1M tokens | |
| Cached input (read) | $0.75 / 1M tokens | 75% off input |
Aion 3.5 providers
2 providers serve it, including Kilo Gateway and NanoGPT. Each host sets its own price and limits, so the cheapest one is not always the one with the longest context.
| Provider | Input /M | Output /M | Cache read /M | Context | Max output |
|---|---|---|---|---|---|
| Kilo Gateway | $3 | $6 | $0.75 | 262K | 33K |
| NanoGPT | $3 | $6 | $0.75 | 262K | 33K |
What Aion 3.5 costs per month
Pick a workload close to yours or type your own volumes.
Supported request parameters
What you can set when you call Aion 3.5 through an OpenAI compatible API.
- Tools
tools - Reasoning
reasoning
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Aion 3.5 questions
How much does the Aion 3.5 API cost?
$3 per million input tokens and $6 per million output tokens, with cached input at $0.75. The estimator on this page turns that into a monthly bill for your own workload.
What is the context window of Aion 3.5?
262,144 tokens of input, and it can write up to 32,768 tokens in one reply. As a rough guide, a million tokens is around 750,000 English words.
Which providers serve Aion 3.5?
2 providers serve it, including Kilo Gateway and NanoGPT. Prices differ by host, so the Providers table on this page lists each one with its input and output price.
Does Aion 3.5 support tool calling?
Yes. It accepts tool definitions, which is what an agent needs to call your APIs.
Is Aion 3.5 open source?
No. AionLabs serves it through an API only, so you cannot download the weights or host it yourself.
When was Aion 3.5 released?
Sep 23, 2026.
Catalog data from models.dev (MIT licensed), refreshed daily, last on Oct 15, 2026. The summary is written from these facts.