Choose AionLabs: Aion 3.5 Mini if…
No advantage on the data we track — pick it for provider preference or output quality on your own prompts.
AionLabs: Aion 3.5 Mini vs XingChen: Xing4.0 29B A4B (free)
XingChen: Xing4.0 29B A4B (free) comes out ahead on the data we track: 4 advantages and none for AionLabs: Aion 3.5 Mini.
Key numbers
| Spec | AionLabs: Aion 3.5 Mini | XingChen: Xing4.0 29B A4B (free) |
|---|---|---|
| Provider | Aion Labs | Xingchen Agi |
| Input price (per 1M tokens) | $0.70 | $0 |
| Output price (per 1M tokens) | $1.40 | $0 |
| Blended price (3:1 input/output) | $0.87 | $0 |
| Cheaper than … of all models we track | 42% | 90% |
| Context window | 262K tokens (~393 pages) | 262K tokens (~393 pages) |
| Larger context than … of all models | 48% | 48% |
| Max output per response | 33K tokens (~24,600 words) | 236K tokens (~176,900 words) |
| Input types | text | text |
| Output types | text | text |
| Free variant | No | Yes |
| Listed since | 2026-09-23 | 2026-10-16 |
What it costs for real workloads
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 Mini | XingChen: Xing4.0 29B A4B (free) | Difference |
|---|---|---|---|
| Customer-support chatbot 50,000 conversations — each a 6-turn conversation (1,500 in / 400 out tokens) | $80.50 | $0 | XingChen: Xing4.0 29B A4B (free) saves $80.50 |
| RAG search over documents 20,000 questions — each a question answered from ~8 retrieved passages (6,000 in / 500 out tokens) | $98.00 | $0 | XingChen: Xing4.0 29B A4B (free) saves $98.00 |
| 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) | $101 | $0 | XingChen: Xing4.0 29B A4B (free) saves $101 |
| Batch summarisation 10,000 documents — each a 6,000-word report summarised to a page (8,000 in / 600 out tokens) | $64.40 | $0 | XingChen: Xing4.0 29B A4B (free) saves $64.40 |
| Long-document analysis 500 documents — each a 150-page contract or codebase read in one pass (100,000 in / 2,000 out tokens) | $36.40 | $0 | XingChen: Xing4.0 29B A4B (free) saves $36.40 |
Capabilities side by side
| Capability | AionLabs: Aion 3.5 Mini | XingChen: Xing4.0 29B A4B (free) | 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 | ✓ Yes | spend extra tokens thinking before answering hard problems |
| Image input | — | — | read screenshots, charts and scanned pages |
| Audio input | — | — | take speech or audio directly |
| File / PDF input | — | — | accept documents without your own parsing step |
| Image output | — | — | generate images, not just text |
| Built-in web search | — | — | answer from live web results |
| Seed (reproducible sampling) | — | ✓ Yes | repeat a generation for tests and evals |
| Log-probabilities | — | — | read token confidence for classification and scoring |
From each model's published parameters and input/output types. “—” means not advertised, not proven absent.
Price history
- AionLabs: Aion 3.5 Mini: price unchanged since we started tracking it on 2026-09-24.
- XingChen: Xing4.0 29B A4B (free): price unchanged since we started tracking it on 2026-10-17.
Which should you choose?
Choose XingChen: Xing4.0 29B A4B (free) if…
- cost matters at scale — it is 100% cheaper on a typical 3:1 input/output mix ($0 vs $80.50 a month for 50,000 support chats)
- you need seed (reproducible sampling) — to repeat a generation for tests and evals; AionLabs: Aion 3.5 Mini does not advertise it
- you generate long outputs in one go — up to 236K tokens (about 176,900 words) per response
- you want to prototype at zero cost — a free variant is listed
Frequently asked questions
Is AionLabs: Aion 3.5 Mini better than XingChen: Xing4.0 29B A4B (free)?
XingChen: Xing4.0 29B A4B (free) comes out ahead on the data we track: 4 advantages and none for AionLabs: Aion 3.5 Mini.
Which is cheaper, AionLabs: Aion 3.5 Mini or XingChen: Xing4.0 29B A4B (free)?
XingChen: Xing4.0 29B A4B (free) is cheaper: $0 vs $0.87 per 1M tokens at a typical 3:1 input/output mix, 100% less. For 50,000 support conversations a month that is $0 against $80.50.
How much do AionLabs: Aion 3.5 Mini and XingChen: Xing4.0 29B A4B (free) cost per million tokens?
AionLabs: Aion 3.5 Mini costs $0.70 per 1M input tokens and $1.40 per 1M output tokens; XingChen: Xing4.0 29B A4B (free) costs $0 input and $0 output. Output tokens are billed separately, so long answers shift the gap.
Which has the bigger context window, AionLabs: Aion 3.5 Mini or XingChen: Xing4.0 29B A4B (free)?
Both take 262K tokens per request — roughly 393 pages of text.
Do AionLabs: Aion 3.5 Mini and XingChen: Xing4.0 29B A4B (free) support function calling and JSON output?
Tool calling — AionLabs: Aion 3.5 Mini: yes, XingChen: Xing4.0 29B A4B (free): yes. JSON-schema structured output — AionLabs: Aion 3.5 Mini: yes, XingChen: Xing4.0 29B A4B (free): yes.
Can AionLabs: Aion 3.5 Mini or XingChen: Xing4.0 29B A4B (free) read images?
Neither accepts image input — both are text-in models.
Is AionLabs: Aion 3.5 Mini or XingChen: Xing4.0 29B A4B (free) free to use?
XingChen: Xing4.0 29B A4B (free) has a free variant (xingchen-agi/xing4.0-29b-a4b:free). Free variants usually carry tighter rate limits.
What is the maximum output length of AionLabs: Aion 3.5 Mini and XingChen: Xing4.0 29B A4B (free)?
AionLabs: Aion 3.5 Mini can write up to 33K tokens (about 24,600 words) per response; XingChen: Xing4.0 29B A4B (free) up to 236K (about 176,900 words).
When were AionLabs: Aion 3.5 Mini and XingChen: Xing4.0 29B A4B (free) released?
AionLabs: Aion 3.5 Mini was listed on 2026-09-23; XingChen: Xing4.0 29B A4B (free) on 2026-10-16.
About the two models
AionLabs: Aion 3.5 Mini
Aion 3.5 Mini is a multi-model roleplaying and storytelling system from AionLabs, built on the GLM family of models. It is the smaller, lower-cost sibling of Aion 3.5 and uses...
Full AionLabs: Aion 3.5 Mini specs →XingChen: Xing4.0 29B A4B (free)
Xing4.0-29B-A4B is an open-weight mixture-of-experts language model from China Telecom's AI team (TeleAI) and the successor to the TeleChat series. It has 29B total parameters with 4B active per token...
Full XingChen: Xing4.0 29B A4B (free) specs →