Headlines and subject lines

Do4U writes several variants of headlines for three uses: pages (title and H1), newsletters (subject line and preheader) and ads (short and long line). Describe the topic or paste the text, then choose tone, number of variants and language; by default the lines come in the language of your input. The code counts every line in characters as people see them. A line that is too long or too short is marked, not hidden, and if too few variants fit, the result says so.

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Who it is for

For marketers, shop owners and editors who need a good headline, subject line or ad text quickly and want to know before they publish whether it fits.

Typical uses

Find a page title and H1 for a new landing page
Write subject lines and preheaders for a newsletter
Try several short and long lines for a search ad
Shorten a headline that is too long for the search result

Example

Input

Kind: newsletter, 5 variants Spring sale in our garden shop: seeds, tools and pots, free delivery from 40 euros

Result

Subject line (34/50): Spring sale: seeds, tools and pots Preheader (66/100): Free delivery from 40 euros – plan your garden before the weekend. Length check: all 5 requested variants are within the limits.

A fixed example, shortened. Real results are AI-generated: please check them.

Price and limits

Price: 1 credit per task
Available with: Free, With package
Input limit: Free: 6,000 characters, packages: 6,000 characters

Privacy

Processed on our own servers in the EU (Poland). Inputs and results are deleted after 7 days (Free) or 30 days (packages), or right after you see the result if you choose not to store them. Images are deleted right after processing.

In the API

Tool name: headlines. Create a job with POST /api/v1/jobs and fetch the result with GET /api/v1/jobs/{id}. You find your API key in your account.

curl -X POST https://do4u.eu/api/v1/jobs \
  -H "Authorization: Bearer d4u_…" -H "Content-Type: application/json" \
  -d '{"tool": "headlines", "text": "…"}'

Full API documentation →

Questions and answers

How are the lengths counted?

In characters as people see them (graphemes), so an emoji or an Arabic word with vowel marks counts once. The limits suit search results, inboxes and ads, and the Do4U admin can change them.

What happens if a variant is too long?

It stays in the list with its length and a mark, so you can shorten it by hand. If too few variants fit the limits, the result tells you how many do. If none fits, Do4U asks again, and after the third attempt the task costs nothing.

Which languages are possible?

By default the lines come in the language of your input, which the code detects. You can also choose one of ten target languages.

Is my text stored?

Only as long as needed: 7 days on Free, 30 days with a package – or not at all if you choose not to store it. Processing happens on our own servers in the EU (Poland).

Can I use the result right away?

Results are AI-generated. Please read them before you publish or send them.