Hemmingway is an AI lab and a writing app. Its model, Hemmingway-1, is a 27-billion-parameter language model with open weights under the Apache-2.0 licence, built on Qwen3.8-27B and trained for writing that sounds like a person wrote it: emails, messages, replies, letters and short stories. You can use it in the Hemmingway apps for Mac, Windows and Android, in the browser at hemmingway.io, through an OpenAI-compatible API, or by downloading the weights and running it yourself.
The name is spelt with two m's. Hemmingway is not connected to the writer Ernest Hemingway, and it is not the Hemingway Editor, a separate readability tool from a different company.
The short version
| What it is | An AI lab, its writing model and its apps |
|---|---|
| Model | Hemmingway-1 |
| Size | 27 billion parameters |
| Built on | Qwen3.8-27B |
| Context | 262,144 tokens |
| Licence | Apache-2.0, including commercial use |
| Weights | huggingface.co/Altworld/Hemmingway-1 |
| Code | github.com/lukeckprobierts/Hemmingway-1 |
| Apps | Mac, Windows, Android and the web |
| API model id | hemmingway-27b, OpenAI-compatible |
| Website | hemmingway.io |
The model: Hemmingway-1
Hemmingway-1 is Hemmingway's own model. It was built for talking to people and for writing, and it is meant to give you the text you asked for rather than a menu of options with notes attached. Ask most models for a text to your landlord and you get three versions and a paragraph explaining them. Hemmingway-1 gives you the text.
It thinks before it answers, at its highest level unless you ask for less. It reads pictures, supports function calling in OpenAI's format, and writes replies of up to 32,768 tokens, thinking included.
How it scores
Hemmingway tests its model against the largest models available. Three of the tests below are Hemmingway's own benchmarks; EQ-Bench 4 is public, and Hemmingway ran it with the official harness.
| Test | What it measures | Hemmingway-1 | Where it placed |
|---|---|---|---|
| CommunicationBench (ours) | Everyday writing, texts and emails | 1026 | First, level with Fable 5.1 |
| Human-Likeness (ours) | Which of two texts a person wrote | 1032 | First, 26 points clear |
| EQ-Bench 4 (public) | Emotional intelligence | 1330 | Third, behind Fable 5 and Kimi K3 |
| StoryBench (ours) | Creative writing | 1197 | Level with Kimi K3, behind Fable 5 Max and GLM-5.3 |
Our own tests are blind: answers are shuffled, every matchup is run in both orders, and the judge is a model that is not one of those being judged. All the scores are on the model card.
What it is good at
- Emails, texts and replies, especially the hard ones: saying no, asking for money back, telling someone something they will not like.
- Writing that reads like a person put it down, not a machine.
- Turning rough notes into a paragraph or a message in your voice.
- Letters, speeches, cards, poems and short stories.
What it is not good at
- Long fiction. Larger story models write better novels and long chapters. Fable 5 Max and GLM-5.3 scored higher on StoryBench.
- Being trusted where a wrong answer costs you. It can be wrong and still sound certain, and it will not always notice. Do not use it for medical, legal or money decisions; check those against a real source or a real person.
- Languages other than English. It is English-first.
- Being a general assistant. It is built for writing, not for code or research.
The apps
The Hemmingway app runs on Mac, Windows and Android, and in the browser at /app/. In it you can:
- ask it to write anything, from a two-line text to a short story;
- tell it who people are, in People, so it writes to your boss, a client or your sister the way you would;
- keep a Memory of things it should know, which you can read, change or delete line by line;
- have it look things up, read pictures and files you attach, and save what it writes as a PDF or a Markdown file.
In the apps for Mac, Windows and Android there is an Inbox. Connect your mail and it puts your mail and chats in one list and drafts each reply for you to read and send. It works with Gmail and Outlook, and the same Inbox holds WhatsApp, Slack and Teams, and iMessage on the Mac. Autopilot, in the Mac and Android apps on paid plans, can answer the easy messages by rules you set. It is off until you switch it on, and everything it does is listed with the reason.
There is a free trial with no card needed. For plans, see /pricing/.
The apps are not yet signed by Apple or Microsoft or listed in the Play Store, so your computer or phone asks once before opening them.
The API
The same model is available through an OpenAI-compatible API. Requests go to https://hemmingway.io/v1 with a key from the API platform and the model hemmingway-27b. Code that already uses OpenAI's SDKs needs the base URL, the key and the model name changed.
It supports streaming, function calling, up to four pictures a request, and control over thinking with reasoning_effort or enable_thinking. A key can draw on prepaid credit or on the allowance of your app plan. Web search and page reading are part of the app, not the API. The full reference is in the docs.
Running it yourself
Because the weights are open, you can run Hemmingway-1 on your own hardware. With vLLM:
vllm serve Altworld/Hemmingway-1 --max-model-len 262144
It also loads in Transformers as a normal chat model. The README on GitHub has a full example, and there is more on open models for writing.
Try HemmingwayDownload the app
The name
Hemmingway has two m's. The model is Hemmingway-1, the app is Hemmingway, and the site is hemmingway.io.
- Not Ernest Hemingway. The American novelist is spelt with one m. Hemmingway has no connection to him or his estate.
- Not the Hemingway Editor. Hemingway Editor, also with one m, is a readability tool at hemingwayapp.com that highlights hard-to-read sentences in what you wrote. It is a different product from a different company. Which is which.
If you search for "Hemmingway AI" and land on either of those, that is why.
Privacy
Hemmingway never trains its models on your chats, memory or People. On the web and on Android you can keep chats only on your device. The privacy page lists everything that is kept.
Common questions
What is Hemmingway AI?
Hemmingway is an AI lab and writing app whose model, Hemmingway-1, writes emails, messages and stories that sound like a person wrote them. Hemmingway-1 is a 27B open-weights model under Apache-2.0, built on Qwen3.8-27B. You can use it in apps for Mac, Windows, Android and the web, or through an OpenAI-compatible API.
Is Hemmingway the same as the Hemingway Editor?
No. Hemmingway, with two m's, writes for you. Hemingway Editor, with one m, is a separate tool from a different company that highlights hard-to-read sentences in text you have already written.
Is Hemmingway-1 open source?
Yes. The weights are on Hugging Face at huggingface.co/Altworld/Hemmingway-1 and the code is on GitHub at github.com/lukeckprobierts/Hemmingway-1, both under Apache-2.0, which allows commercial use.
What model is Hemmingway built on?
Hemmingway-1 is built on Qwen3.8-27B and trained further for writing. It has the same 27B size and a 262,144-token context. How it differs from the base model.
Is Hemmingway free?
There is a free trial with no card needed, and the model weights are free to download and run. For paid plans and API costs, see /pricing/ and the API platform.