Aion-3.5 overview
Aion-3.5 by AionLabs
Aion 3.5 is a multi-model roleplaying and storytelling system from AionLabs that uses multiple specialized models to generate a response, and it supports tool calling for richer interactive fiction.
Aion-3.5 specs
- Model ID
aion-labs/aion-3.5- Developer
- AionLabs
- Context window
- 262,144 tokens
- Max output
- 32,768 tokens
- Input
- Text
- Output
- Text
- API
- OpenAI-compatible, base URL
https://api.aimlapi.com/v1
What Is Aion-3.5 API?
Aion 3.5 is a multi-model roleplaying and storytelling system from AionLabs, built on the GLM family of models.
It uses a collaborative generation process in which multiple specialized models each contribute to a response, producing stronger narrative structure and more compelling tension and conflict.
Technical Reference
| Developer | AionLabs |
|---|---|
| Model ID | aion-labs/aion-3.5 |
| Release Date | September 23, 2026 |
| Context Window | 262,144 tokens (~262K) |
| Max Output Tokens | 32,768 tokens |
| Modalities | Text → Text |
| Capabilities | file input, parallel tool calls, reasoning, streaming, structured (JSON schema) output, tool/function calling, web search |
What Aion-3.5 Brings to the Table
Model type
Multi-model roleplaying and storytelling system.
Architecture
Built on the GLM family of models.
Generation approach
Uses collaborative generation, where multiple specialized models contribute to one response.
Focus
Designed to produce stronger narrative structure and more compelling tension and conflict.
Where Aion-3.5 Makes the Most Sense
Roleplaying
Suited to interactive roleplaying experiences.
Storytelling
Suited to narrative generation and story development.
Narrative writing
Useful for outputs that benefit from stronger structure and dramatic tension.
Aion-3.5 vs the Alternatives
Aion 3.5 Mini
AionLabs also offers Aion 3.5 Mini, which is described as the smaller, lower-cost sibling of Aion 3.5 and uses the same collaborative generation process.
Sources: https://openrouter.ai/aion-labs/aion-3.5 · https://openrouter.ai/provider/aion-labs · https://openrouter.ai/aion-labs
Use cases
Aion-3.5 is documented as suited for roleplaying and storytelling, where its collaborative generation process is used to produce stronger narrative structure and more compelling tension and conflict.
It is also documented for richer interactive fiction, with support for tool calling noted in that context.
It is further described as handling mature and darker themes with nuance.
Another documented use case is chat-style use through a frontend for power users that emphasizes character creation, roleplay, and prompt customization.
Capabilities
- File input
- Reasoning
- Streaming
- Structured outputs
- Function calling
- Web search
Aion-3.5 API pricing
| Usage | Price | Unit |
|---|---|---|
| Input | $3.17 | 1M tokens |
| Output | $6.35 | 1M tokens |
| Cached input | $0.7935 | 1M tokens |
Prices from the AI/ML API price list, checked on Nov 4, 2026.
Aion-3.5 vs other models: token prices
AI/ML API input and output rates for 5 models, per million tokens.
| Model | Input | Output |
|---|---|---|
| Aion-3.5 | $3.17 | $6.35 |
| Aion-3.5-Mini | $0.7406 | $1.48 |
| Aion-3.0-Mini | $0.7406 | $1.48 |
| Aion-2.0 | $0.8464 | $1.69 |
| Aion-3.0 | $3.17 | $6.35 |
How to use the Aion-3.5 API
View docs
Build with your agent
Give your agent the model details, code and documentation.
1Get your API key
Create API keyexport AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"2Make your first request
curl 'https://api.aimlapi.com/v1/chat/completions' \
-H "Authorization: Bearer $AIMLAPI_KEY" \
-H 'Content-Type: application/json' \
-d '{
"model": "aion-labs/aion-3.5",
"messages": [
{
"role": "user",
"content": "Write a haiku about the ocean."
}
]
}'import os
import requests
headers = {
"Authorization": f"Bearer {os.environ['AIMLAPI_KEY']}",
"Content-Type": "application/json",
}
payload = {
"model": "aion-labs/aion-3.5",
"messages": [
{
"role": "user",
"content": "Write a haiku about the ocean."
}
]
}
response = requests.post("https://api.aimlapi.com/v1/chat/completions", headers=headers, json=payload, timeout=120)
response.raise_for_status()
print(response.json())const response = await fetch("https://api.aimlapi.com/v1/chat/completions", {
method: "POST",
headers: {
Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
"Content-Type": "application/json",
},
body: JSON.stringify({
"model": "aion-labs/aion-3.5",
"messages": [
{
"role": "user",
"content": "Write a haiku about the ocean."
}
]
}),
});
if (!response.ok) throw new Error(`HTTP ${response.status}`);
console.log(await response.json());Models similar to Aion-3.5
Aion-3.5 FAQ
How much does Aion-3.5 cost?
Aion-3.5 costs $3.17 input and $6.35 output per 1M tokens on AI/ML API, billed as you go with no subscription.
What kind of model is Aion-3.5 on AI/ML API?
Aion-3.5 is a multi-model roleplaying and storytelling system from AionLabs built on the GLM family of models.
How does Aion-3.5 generate responses?
It uses a collaborative generation process where multiple specialized models each contribute to a response. This is intended to produce stronger narrative structure and more compelling tension and conflict.
What is Aion-3.5 best used for?
It is optimized for roleplaying and storytelling tasks. The model is focused on narrative quality rather than general-purpose chat alone.
Is Aion-3.5 a single-model or multi-model system?
Aion-3.5 is a multi-model system. Multiple specialized models work together during generation.
Which model family is Aion-3.5 based on?
Aion-3.5 is built on the GLM family of models.
Does Aion-3.5 support tools?
Yes, the model supports tools. It can work with function-style tool use.
Does Aion-3.5 support structured output?
Yes, structured output is supported for this model.
Does Aion-3.5 support streaming responses?
Yes, streaming is supported.
Can Aion-3.5 be used with parallel tool calls?
Yes, parallel tool calls are supported.