---
title: "Cold Email Subject Line Generator"
description: "Generate cold email subject lines for a described audience and offer."
source: "https://www.mailmark.dev/tools/subject-line-generator"
site: "Mailmark"
---

# Cold Email Subject Line Generator

Generate cold email subject lines tailored to your industry, your offer, and the tone you want.

## API

```bash
curl -X POST https://www.mailmark.dev/api/tools/generate-subject-lines \
  -H "Content-Type: application/json" \
  -d '{"industry":"SaaS","offer":"a 15 minute demo","tone":"direct"}'
```

Valid tones: `casual`, `professional`, `direct`, `friendly`, `urgent`.

Rate limited per IP. Errors come back as structured JSON with `error`, `code`, and `hint`.

Related: [Email Deliverability Guide](/guides/email-deliverability), [Spam Score Tester](/tools/spam-score-tester).

---

Mailmark - email hosting and campaigns for your own domain. Canonical page: https://www.mailmark.dev/tools/subject-line-generator | [llms.txt](https://www.mailmark.dev/llms.txt) | [OpenAPI](https://www.mailmark.dev/openapi.json) | [sitemap](https://www.mailmark.dev/sitemap.xml)