Audit your app
How to Write Website Copy: One Promise, Specific Words, One Action
How to write website copy for a small app: start with one promise sentence, build the first screen from it, and ask for one clear action. Try it today.
How to write website copy comes down to 3 moves. Write one sentence that says who the product is for and what they get. Build the first screen from that sentence: a headline, a short line under it, and one button. Then keep every later line tied to that promise, so a first-time visitor never has to guess. That is website copywriting for a small app.
Copy often gets written last, in a hurry, after the app works. That is how "Get started" ends up on a button. We wrote this for the blank page. If your words already exist and you want to judge them, our website content audit guide is the one to use.
What does website copywriting have to do?
It has to answer 3 questions for someone who has never heard of you: what is this, is it for me, and what do I do next. Nothing else on the page matters until those are settled.
That maps onto 2 of the six areas our audit scores. Clarity and Promise asks: does the headline say what this is, in one sentence, and does the rest of the page agree with it? Conversion and The Ask asks whether the call to action asks for something specific. When we write a first screen, those 2 questions are the ones we hold it against.
What belongs on the first screen?
3 things: a headline, one supporting line, and one button. Anything else you add competes with them.
Plain, tight writing has some old evidence behind it. In a 1997 test by Nielsen Norman Group (NN/g), 51 users tried 5 versions of a 7-page information website. The concise version, the scannable version, and the objective, no-hype version each scored higher on usability than a promotional original, and the version that combined all 3 scored 124% higher (NN/g, page dated 1 January 1997, read 8 October 2026). It is an old test of one kind of site, and it measured usability, not sales, so we treat it as a direction and not a promise.
How do you write the promise sentence?
Before you write a headline, fill in this sentence in plain words:
[Person] can [result] by [what they give you].
The person is a specific kind of human, not "teams" or "users". The result is what changes for them. What they give you is the input: a link, a photo, a date, an email address.
Then run one check. Say it to a friend who knows nothing about your product. If they ask "wait, what does it actually do?", the sentence is not finished. Digital.gov's plain-language guide says to tell your audience why the material matters to them (Digital.gov, page published 11 September 2025, read 8 October 2026). Your promise sentence is the short version of that. For the line-by-line test of whether a sentence could sit on any other product's page, use the swap-the-name test in the website content audit guide.
How do you build the first screen from it?
Take the 3 parts of your sentence and give each one a job:
- Headline: the result, in plain words.
- Line under it: the person and the input, so a visitor can tell it is for them.
- Button: the next step, named for what happens when it is pressed.
Cut every adjective that does not change what a visitor would do. "Seamless" and "powerful" are claims with nothing behind them, so we drop them and show the step they were hiding.
How do you pick the one action?
Ask what a happy visitor would do next, give that one thing the only strong button on the first screen, and let button wording and the path to it wait for our CRO audit guide.
What do website copy examples look like on a first screen?
Hypothetical example: a made-up houseplant watering tracker. The promise sentence: "People who forget which plant is thirsty can see today's list by adding each plant and its watering gap once." Here is that one sentence pulled apart and placed on the page, as a draft to test, not proof of better results.
| Piece of the promise sentence | Where it lands | Words on the page |
|---|---|---|
| The result: "see today's list" | Headline | Know which plant to water today |
| The person: "people who forget which plant is thirsty" | Line under the headline | Forget which plant is thirsty? Add each plant once, then see the ones that are due each morning. |
| The input: "each plant and its watering gap" | First feature line | Tell us a plant needs water every 7 days. It shows up on day 7. |
| The next step | Button | Add my first plant |
Every word on the first screen traces back to one piece of the sentence. If a line has no home in the table, we cut it or rewrite the sentence.
How do you write the lines below the first screen?
Give each section one job, and make it support the promise. For the plant tracker, that might be 3 sections: a "how it works" line for each step (add a plant, set the gap, tick it off), a look at what the morning list shows, and an answer to the question most likely to stop someone, such as "Do I need an account?" Then repeat the same button once at the bottom.
Keep every claim you can prove and drop the rest. If you have no real customer quotes yet, leave the testimonial section out and do not invent one. Before you publish, search the page for leftover template text, such as a placeholder company name or "Lorem ipsum". Our audit's Trust and Legitimacy area looks for the signals a customer checks before they trust you with money, and filler undoes them.
What if an AI tool drafts the words?
It can give you good raw material if you hand it your promise sentence and ask for 5 headline options. Left alone, it will tend to write lines that fit many products, so we pick the option closest to your sentence and edit it until it is yours. The swap-the-name test in our content audit guide shows you which lines still need work.
When we score an app, the "Slop tells" line under Clarity and Promise is where vague, stand-in copy shows up.
Will it still work on a phone?
Check it before you call the copy done. Our audit reads desktop and mobile screenshots, and the Mobile and Access question is whether the primary action is visible on a real phone screen without scrolling, pinching, or guessing. A long headline can push your one button out of sight.
As a rule of thumb from us, not a tested limit: if the headline wraps past 3 lines on your phone, shorten it. Open the page on your own phone before you share it.
How do you check what you wrote?
First, read the first screen as a first-time visitor would. Cover your logo, read only the headline, line, and button, and ask the 3 questions from the start of this guide.
Second, get an outside read. Ours is an AI audit scored against a fixed rubric, so no person reads your app. We score your public pages out of 100, rank the fixes, and list what works and what reads as slop in each of the six areas. We read public pages only, nothing behind a login, and the audit is not a security review or a full accessibility audit. If you pay and the report is not useful, you can request a full refund within 24 hours of the report being delivered, and we refund automatically if an audit cannot finish.
What is a good first step today?
Give it 15 minutes. Fill in the promise sentence. Write a headline from it, one line under it, and one button label that says what happens next. Put all 3 on your first screen, open it on your phone, and leave everything below for tomorrow.