Neither wins outright: AionLabs: Aion 3.5 is the pick when you need to fit long inputs in one request, OpenAI: GPT-4o-mini when cost matters at scale.
| Spec | AionLabs: Aion 3.5 | OpenAI: GPT-4o-mini |
|---|---|---|
| Provider | Aion Labs | OpenAI |
| Input price (per 1M tokens) | $3.00 | $0.15 |
| Output price (per 1M tokens) | $6.00 | $0.60 |
| Blended price (3:1 input/output) | $3.75 | $0.26 |
| Cheaper than … of all models we track | 17% | 64% |
| Context window | 262K tokens (~393 pages) | 128K tokens (~192 pages) |
| Larger context than … of all models | 48% | 15% |
| Max output per response | 33K tokens (~24,600 words) | 16K tokens (~12,300 words) |
| Input types | text | text, image, file |
| Output types | text | text |
| Free variant | No | No |
| Listed since | 2026-09-23 | 2024-07-18 |
Monthly cost at list price for five common workloads. Token counts per unit are stated so you can scale them to your own traffic. A workload that does not fit a model's context window is marked rather than priced.
| Workload (per month) | AionLabs: Aion 3.5 | OpenAI: GPT-4o-mini | Difference |
|---|---|---|---|
| Customer-support chatbot 50,000 conversations — each a 6-turn conversation (1,500 in / 400 out tokens) | $345 | $23.25 | OpenAI: GPT-4o-mini saves $322 |
| RAG search over documents 20,000 questions — each a question answered from ~8 retrieved passages (6,000 in / 500 out tokens) | $420 | $24.00 | OpenAI: GPT-4o-mini saves $396 |
| Coding / tool-using agent 2,000 tasks — each a multi-step task with tool calls and file context (60,000 in / 6,000 out tokens) | $432 | $25.20 | OpenAI: GPT-4o-mini saves $407 |
| Batch summarisation 10,000 documents — each a 6,000-word report summarised to a page (8,000 in / 600 out tokens) | $276 | $15.60 | OpenAI: GPT-4o-mini saves $260 |
| Long-document analysis 500 documents — each a 150-page contract or codebase read in one pass (100,000 in / 2,000 out tokens) | $156 | $8.10 | OpenAI: GPT-4o-mini saves $148 |
| Capability | AionLabs: Aion 3.5 | OpenAI: GPT-4o-mini | What it lets you do |
|---|---|---|---|
| Tool / function calling | ✓ Yes | ✓ Yes | call your APIs and run agent loops |
| Structured output (JSON schema) | ✓ Yes | ✓ Yes | return JSON that validates against your schema |
| Reasoning / thinking mode | ✓ Yes | — | spend extra tokens thinking before answering hard problems |
| Image input | — | ✓ Yes | read screenshots, charts and scanned pages |
| Audio input | — | — | take speech or audio directly |
| File / PDF input | — | ✓ Yes | accept documents without your own parsing step |
| Image output | — | — | generate images, not just text |
| Built-in web search | — | ✓ Yes | answer from live web results |
| Seed (reproducible sampling) | — | ✓ Yes | repeat a generation for tests and evals |
| Log-probabilities | — | ✓ Yes | read token confidence for classification and scoring |
From each model's published parameters and input/output types. “—” means not advertised, not proven absent.
Neither wins outright: AionLabs: Aion 3.5 is the pick when you need to fit long inputs in one request, OpenAI: GPT-4o-mini when cost matters at scale. In short: AionLabs: Aion 3.5 when you need to fit long inputs in one request, you need reasoning / thinking mode, you generate long outputs in one go, you want the newer model; OpenAI: GPT-4o-mini when cost matters at scale, you need image input, you need file / PDF input, you need built-in web search, you need seed (reproducible sampling), you need log-probabilities.
OpenAI: GPT-4o-mini is cheaper: $0.26 vs $3.75 per 1M tokens at a typical 3:1 input/output mix, 93% less. For 50,000 support conversations a month that is $23.25 against $345.
AionLabs: Aion 3.5 costs $3.00 per 1M input tokens and $6.00 per 1M output tokens; OpenAI: GPT-4o-mini costs $0.15 input and $0.60 output. Output tokens are billed separately, so long answers shift the gap.
AionLabs: Aion 3.5: 262K tokens, about 393 pages, against 128K (about 192 pages) for OpenAI: GPT-4o-mini.
Tool calling — AionLabs: Aion 3.5: yes, OpenAI: GPT-4o-mini: yes. JSON-schema structured output — AionLabs: Aion 3.5: yes, OpenAI: GPT-4o-mini: yes.
Only OpenAI: GPT-4o-mini accepts image input; AionLabs: Aion 3.5 is text-only for input.
No free variant is listed for either; both are pay-per-token.
AionLabs: Aion 3.5 can write up to 33K tokens (about 24,600 words) per response; OpenAI: GPT-4o-mini up to 16K (about 12,300 words).
AionLabs: Aion 3.5 was listed on 2026-09-23; OpenAI: GPT-4o-mini on 2024-07-18.
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...
Full AionLabs: Aion 3.5 specs →GPT-4o mini is OpenAI's newest model after [GPT-4 Omni](/models/openai/gpt-4o), supporting both text and image inputs with text outputs. As their most advanced small model, it is many multiples more affordable...
Full OpenAI: GPT-4o-mini specs →