Every phone rewrites your messages now. Almost none of them tells you what yours says.

Open Messages on a recent iPhone, select what you’ve typed, and tap Writing Tools¹. You get proofreading, a rewrite, and a choice of Friendly, Professional or Concise. It costs nothing and there’s no account to make.

I run a paid app called Subtext that overlaps with that. It tells you how your message will read to the person about to receive it, before you send it. So the fair question, and I get asked it in App Store reviews, is why anyone would give me money for something Apple bundles for nothing.

Subtext earns its price in one case, a message that matters, where you need to know how it will read before you send it. The table at the end sorts the rest by job. You can see Subtext read a draft in the section on the job most of them leave to you, and a second draft, a defensive reply to a mother, in the Grammarly section, the kind of message a work-tuned tool is not calibrated for.

Two things you should know before you read the rest

The first is obvious. I co-founded Subtext, so I’m not a neutral party. The section called “Where the big ones beat us” exists because a comparison written by a founder is worthless without one.

The second is stranger. Subtext runs on Anthropic’s models, which our privacy policy² names alongside Deepgram for voice and OpenAI for read-aloud. So Claude is simultaneously our supplier and one of the products in this article. We pay a competitor for the engine. That’s an odd position to be in, and I’d rather you heard it from me.

I checked everything below on 11 August 2026, and rechecked Apple’s Siri AI and privacy pages, Grammarly’s tone and pricing pages and our own privacy policy on 26 September 2026.

What all of them already do, and do well

First, the baseline. Every product in this article can take a message you’ve written and give you back a cleaner version. Grammar, spelling, length, and a formality dial from casual to professional. On that job they range from good to excellent, and several are free.

If that’s what you want, you’re finished. Use what’s on your phone. The rest of this article is about a narrower thing.

The job most of them leave to you

Every one of them answers “make this better”. Grammarly is the one that also labels how your writing comes across without you asking, and it is tuned for work; I compare it with Subtext job by job in Subtext vs Grammarly for personal messages and tone checking. ChatGPT and Claude will answer “tell me what this actually says” if you ask it that way and type out the context.

That second question is a different piece of work. It means reading a draft as something a specific person will receive in a specific situation, naming the part that reads as colder or more defensive than you meant, and saying so before you send, not explaining it afterwards. It means taking a screenshot of the thread, or a five-minute voice note you don’t want to listen to again, and working out what the other person is really asking of you. That is the job Subtext takes on, so read this section as my pitch and check it against the feature table below, which only counts what each company documents. The longer version of that pitch is what the Subtext app is, who it’s for, and when to use it.

One line shows the job, in an example made up for the purpose. The draft was “No worries, I’ll just do it myself.”, which is friendly on its face. Subtext named the feeling Disappointment and tagged it Passive-aggressive, because the line “can read as a hidden jab implying the other person let you down”. Its closest version, “No worries, I’ll take care of it myself.”, drops the “just”, and its note says it is “still brief and could read a bit cool”. That is the app’s real output, unedited, and it shows Subtext on one draft, not what any of the other products would do with it.

I don’t think the big companies avoid this job because it’s technically hard. I think they avoid it because telling someone their message sounds passive-aggressive is a rude thing for a phone to do.

Platform features can’t afford to be rude to a billion people. A tool you choose on purpose can.

One study bears on this, though it tested no product, Subtext included. Liu, Kang and Wei ran an online experiment with 208 people imagining a close friend had used AI to help write them a message³. The AI help itself made the message read as less effortful, and that lower perceived effort was what dragged down satisfaction with the friendship and raised uncertainty about where things stood. The detail that matters is that asking another person for help scored no differently from asking AI, on any of it. The problem was never AI. It was outsourcing the effort a message is supposed to carry. That is why Subtext reads your draft back to you before it offers any versions, and keeps the first version close to your own words.

Apple Intelligence is free, everywhere and deliberately incurious

Apple’s Writing Tools work nearly anywhere you can type, including third-party apps, and have shipped since iOS 18.1 and macOS Sequoia 15.1¹. You get proofread, summarise, and rewrite, with Friendly, Professional and Concise as presets. There’s also a “Describe your change” box⁴ where you can type something like “make this more enthusiastic” and get it.

That last feature is better than most people realise. It’s an open-ended instruction slot, which means the ceiling is whatever you can articulate.

I think the word articulate is where it falls down. Writing Tools will do what you ask. It will not tell you what to ask for. It reads your draft as text to improve, never as a message that a specific person is about to receive and interpret. Ask it to make something friendlier and it will. It won’t mention that your third sentence reads as a threat.

Apple’s Siri AI beta on iOS 27 adds a way to ask, with prompts like “How’s this sound?”, in English to start and not yet in the EU⁵. Like ChatGPT and Claude, it gives feedback when you ask for it.

For most messages that gap doesn’t matter. For the ones you rewrite five times, it’s the whole problem.

Google has two different tools, and neither is the one you’d expect

Google has split this into two products.

Magic Compose⁶ sits inside Google Messages and rewrites your draft into a chosen style, and Google describes it as a creative partner rather than a grammar check. The styles lean playful, including one that rewrites you as Shakespeare.

Gemini in Google Messages⁷ is the bigger one, a full assistant inside your texting app, free with a personal Google account and now live in more than 165 countries. You need to be 18 or over with RCS turned on. Google also states plainly that chats with Gemini are not end-to-end encrypted⁷, and I’d flag that before you paste a conversation about your marriage into it.

Between them Google covers drafting and rephrasing comfortably. Neither analyses the emotional reading of what you’re about to send.

Samsung has the most complete free package on any phone

Samsung’s Writing Assist⁸ is the one people underrate. It lives in the keyboard toolbar, and since One UI 7 it works with any keyboard, where it used to need Samsung’s own. You get spelling and grammar, writing style, summarise, bullet points, table, and a Composer that drafts from keywords. Style variants include Professional, Casual, Social, Polite and Emojify, across 16 languages.

In early 2026 Samsung confirmed the core Galaxy AI features stay free with no expiry date, after earlier wording suggested they might not.

If you own a recent Galaxy, you already have a more capable writing assistant than most paid apps sell. I say that as someone who sells one. I sort the paid ones in the best AI writing assistants in 2026, by the problem they actually solve.

Grammarly is the closest thing to us at real scale

Grammarly is the only large player that has taken tone seriously as a distinct problem. Its tone detector⁹ has been running since 2019, and Pro flags sentences likely to be misread and offers rewrites before you send. It runs in a browser extension, desktop apps, a mobile keyboard, Google Docs, and it powers the writing assistant inside Samsung’s keyboard.

Free covers grammar, spelling, tone detection and a monthly allowance of AI prompts. Pro is $12 a month billed annually, or $30 month to month¹⁰. Its parent company renamed itself Superhuman¹¹ in October 2025 while keeping the Grammarly product name.

The difference sits somewhere it took me a while to articulate. Grammarly is calibrated for work. Its idea of a bad message is one that’s unclear, unprofessional, or grammatically wrong. That calibration is correct for the email to your manager and wrong for the message to your mother, where the failure modes are different: sounding cold when you meant careful, sounding defensive when you meant hurt, over-explaining because you’re anxious. Those read as fine writing to a work-tuned tool.

Here is one such message as Subtext read it, in an exchange made up for this example. To a mother’s “I suppose I’ll just spend Sunday on my own again. Don’t worry about me.”, the reply drafted was “Mum, I told you weeks ago I can’t come. Why do you always do this?”, which has nothing wrong with its grammar. Subtext tagged it Generalization and Defensiveness, with Frustration as the feeling, and explained that “Why do you always do this?”, the words it marked, “turns one moment into a pattern and may feel like an attack”. The second version read “Mum, I do care about you being on your own, and I’m sorry Sunday doesn’t work for me. I’d love to see you soon though. Could I call you on Sunday, or pop round another day?” Subtext flagged the call and the other day as its own additions to the reply; the example shows Subtext on one draft and nothing about what Grammarly would do with it.

Grammarly could add this. If they decide personal messaging is worth the attention, they arrive with a mobile keyboard and tens of millions of users.

ChatGPT and Claude can already do everything

Both can do what Subtext does. That’s not false modesty. Paste your draft, describe the relationship, name the tone you want, ask what an AI message checker would flag, and you’ll get a good answer. ChatGPT¹² runs a free tier plus Go at $8, Plus at $20, and Pro tiers above that. Claude¹³ has a free tier with Pro at $20 a month.

So why does a small app survive next to them? Three reasons I can defend.

The instructions are the work. “Paste your draft, describe the relationship, specify the tone, ask what could be misread” is four things to remember at the exact moment you’re least able to think clearly. It’s 11pm and you’re upset. Nobody prompt-engineers at 11pm.

The blank box asks the wrong question. A chat window says “what do you want”. A tool built for one job can ask “who is this going to, and what happened before this message”, which is what determines the answer.

They default to agreeing with you, as I found comparing ChatGPT alternatives for writing. Ask a general assistant whether your angry message is justified and it will usually find a way to say yes, because that’s the shape of a helpful reply to a question phrased that way. The useful answer is often that you’re right and the message will still land badly.

Every one of those is an interface problem rather than a capability one, and interface problems get solved.

Wordtune and DeepL Write are excellent at a different job

I’ll give it a paragraph because people ask. Wordtune¹⁴ does sentence-level rewrites with tone modes, free up to ten rewrites a day, with paid tiers whose prices shift by region. DeepL Write is the best thing available for making non-native English read naturally, with formal, informal, enthusiastic, confident and diplomatic styles.

Both are document tools. Neither reads a conversation, and neither has an opinion about how your message will feel to the person receiving it.

Feature comparison

Y means documented on the company’s own site or support pages. N means it isn’t.

On that last row, our terms say your content is never used to train models, and that our providers may not either². Defaults differ across the others, and some have it switched on until you opt out, so check the setting in whatever you use. That’s a two-minute job worth doing once.

Training is one of four privacy questions. The other three are what leaves your phone, who processes it and how long they keep it. Subtext sends what you give it to the providers our privacy policy names and to our own servers, and deletes a conversation five days after you last use it, or 90 days if you pin it². Memory notes stay in your account until you delete them. Apple runs many Apple Intelligence requests entirely on the device and can send more complex ones to its Private Cloud Compute servers¹⁵. Check all four for whatever you use.

What they cost

Where the big ones beat us

They’re free and already there. There’s nothing to download or sign up for, and for most people that alone settles the question against Subtext.

They’re in the keyboard. Apple, Samsung and Grammarly work where you’re already typing. We make you paste, share or screenshot. Every time someone tells me the app is great but they forget to open it, they’re describing this.

They handle documents better. Grammarly on a long report, DeepL Write on a second-language email, Wordtune on an essay. We built Subtext for messages and it shows outside that.

They aren’t going anywhere. Apple and Google will still ship this in five years.

Which one to use when

That last row is the only one I’d argue about. Everything above it, the free tools win or draw, and I’d rather say that than pretend otherwise.

Subtext is for the moment before you send, when you want to know how it reads and what’s easy to misinterpret. Paste the half-finished draft, screenshot the thread, or hand it the voice note, and it names what your message is about to signal to the person receiving it, then offers versions that still sound like you, without the edge you didn’t mean. It works in 20+ languages. Try Subtext in your browserDownload on the App StoreGet it on Google PlayGet the app

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If you think I’ve been soft on my own app or unfair to a product you work on, tell me. I’ll fix it and say what changed.

Samet Durgun is the co-founder of Subtext, an app that catches the emotional tone of your messages and rewrites them in your own voice. He’s based in Berlin.

Sources

Every link above goes to the primary source where one exists. Checked on 11 August 2026; sources 2, 5, 9, 10 and 15 were rechecked on 26 September 2026. Prices and platform features change often, so confirm before you buy.

1. Apple Support, Use Writing Tools to write, improve, and summarize content on iPhone.
2. Subtext, Terms, privacy and your account.
3. Liu, B., Kang, J., and Wei, L. (2023). Artificial intelligence and perceived effort in relationship maintenance: Effects on relationship satisfaction and uncertainty. Journal of Social and Personal Relationships, 41(5), 1232 to 1252. Online experiment, 208 participants, hypothetical scenarios with a fictional close friend.
4. Apple Support, Use Writing Tools with Apple Intelligence on iPhone.
5. Apple Support, Siri AI: Write with Siri on iPhone. Beta on iOS 27. Checked 26 September 2026.
6. Android, Using Magic Compose: AI for text messages and writing.
7. Google, Use Gemini in Google Messages.
8. Samsung, Enhance your messages with Writing Assist on your Samsung Galaxy (feature description); Samsung, Use Writing assist on Galaxy phones and tablets (16-language, 23-locale support list); SamMobile, One UI 7.0 lets you use Galaxy AI writing tools with any keyboard (any-keyboard support since One UI 7); and Beebom, How to Use AI Writing Assist in One UI 7 on Samsung Phones (Professional/Casual/Social/Polite/Emojify style variants).
9. Grammarly, Writing tone detector and tone suggestions.
10. Grammarly, Pro plans.
11. Grammarly, Grammarly rebrands company as Superhuman.
12. OpenAI, ChatGPT pricing.
13. Anthropic, What is the Pro plan? and Claude plans and pricing.
14. Wordtune, plans and pricing.
15. Apple Support, Apple Intelligence and privacy on iPhone. Checked 26 September 2026.