ChatGPT is OpenAI's general assistant. It writes, codes, researches, explains, and a great deal else. Hemmingway is narrower on purpose: it is built for writing to people, and for making that writing sound like you.
If you want one tool for everything, that is ChatGPT. If most of what you want help with is emails, messages and the things you keep putting off writing, this page is for you.
Hemmingway writes with its own model, Hemmingway-1.5, released on 25 October 2026. Its headline result is AI detectors: 90% of its writing passes GPTZero & Pangram and the top AI detectors on the first try. It is built on Hemmingway-1, our first model, and the benchmark scores below are Hemmingway-1's.
The short version
| Hemmingway | ChatGPT | |
|---|---|---|
| Built for | Writing that sounds like a person | Almost any task |
| Model | Hemmingway-1.5, 27B, open weights | OpenAI's GPT models |
| Passes AI detectors, same 80 asks (our test) | Hemmingway-1.5 92% | GPT-6 Astra 20% |
| Everyday messages (our test) | Hemmingway-1 1026, first | GPT-6 Astra 976 |
| Sounds like a person (our test) | Hemmingway-1 1032, first | GPT-6 Astra 964 |
| EQ-Bench 4 (public) | Hemmingway-1 1330 | GPT-5.5 1316 |
| Long stories (our test) | Hemmingway-1 behind GPT-6 Astra | Stronger |
| Drafts replies from your inbox | Yes, in the apps | Not what it is built around |
| Trains on your chats | Never | See OpenAI's settings |
Passing AI detectors
We gave Hemmingway-1.5 and the biggest models the same 80 everyday asks and ran every answer through GPTZero & Pangram and four of the top open AI detectors. 92% of Hemmingway-1.5's answers read as human. 20% of GPT-6 Astra's did. How the test was run.
Writing emails and messages
We tested Hemmingway-1 and ChatGPT on eighty real email and message requests in blind head-to-head matchups. Hemmingway-1 came first overall, fifty points ahead of GPT-6 Astra.
The widest gap was on hard asks: turning someone down, asking for money back, the message you keep rewriting. Judged on which reply sounded like a person wrote it, GPT-6 Astra's won 9% of the time and Hemmingway-1's 72%.
To be fair to GPT-6 Astra: its messages were short and it rarely buried them in commentary, which many models do. Where it fell behind was in sounding like a person rather than a well-behaved assistant. The full results are here.
Stories
For long fiction, GPT-6 Astra is the stronger writer in our tests. If you are drafting a novel, use a big model. For short pieces that have to sound like someone sat down and wrote them, Hemmingway is built for that. More on creative writing.
Writing as you, to the people you know
This is the main difference in how they work. In Hemmingway you tell it who people are: your boss, a client, your sister. It writes to each of them the way you would, in the language you use with them. It keeps a memory of what it should know, and you can read and change every line.
In the Hemmingway apps for Mac, Windows and Android, it can also read your mail and chats, including Gmail, Outlook, WhatsApp, Slack and Teams, and draft each reply for you to send. How that works.
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. Our privacy page lists everything we keep.
Which to use
- Code, research, maths, general questions: ChatGPT.
- Emails, texts, replies, anything that has to sound like you: Hemmingway.
- Both: plenty of people use a general assistant for thinking and Hemmingway for the words that go out under their name.
Try HemmingwayDownload the app
Common questions
Is Hemmingway better than ChatGPT for writing?
For emails and messages that have to sound like you, it did better in our tests. On the same 80 everyday asks, 92% of Hemmingway-1.5's answers passed AI detectors against 20% of GPT-6 Astra's. Hemmingway-1 scored 1026 against GPT-6 Astra's 976 on everyday messages, and 1032 against 964 on sounding like a person. These are our own tests. For long fiction, and for anything that is not writing, ChatGPT is the stronger choice.
Is Hemmingway built on ChatGPT?
No. Hemmingway runs on our own models. Hemmingway-1.5, the default, is a 27B open-weights model built on Hemmingway-1, which is built on Qwen3.8-27B.
Does Hemmingway train on my chats?
No. 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, and our privacy page lists everything we keep.
Can I use Hemmingway and ChatGPT together?
Yes. Plenty of people use a general assistant for thinking and research, and Hemmingway for the words that go out under their name.