How to Write a Startup One-Liner (With Examples)

Almost every accelerator application starts with the same question in a different form: Y Combinator's "Describe what your company does in 50 characters or less," a16z speedrun's 100-character pitch, Alchemist's 280-character description, SOSV's 140 characters. It's the first thing a reviewer reads, and often the only thing they read before deciding whether to keep reading. Here's how to write one that works.

What a one-liner has to do

A good one-liner lets a stranger answer two questions instantly:

1. What is it?
2. Who is it for?

That's all. Not your vision, not your market size, not your technology stack. If a reader can repeat your one-liner back to you accurately, it works.

The formula

Most great one-liners fit one of three patterns:

1. [Product] for [customer]

• "Payroll for restaurants in Mexico."
• "Scheduling software for home-care agencies."
• "Accounting for freelancers in Germany."

The simplest and usually the best. It works when your product category is familiar.

2. [Known company] for [new market]

• "Shopify for independent pharmacies."
• "Stripe for cross-border payroll in Africa."

It borrows understanding from a famous product. Use it only when the analogy is accurate — a loose analogy confuses more than it helps.

3. [Outcome] for [customer], [how]

• "Cut no-shows in half for dental clinics with automated reminders."
• "Find every carbon credit fraud in minutes, using satellite imagery."

Useful when your category is new and the outcome is the clearest way in.

Words to delete

These words make one-liners vaguer without adding information:

• Platform, solution, ecosystem — say what it actually is.
• Revolutionize, disrupt, reimagine, transform — say what changes.
• AI-powered, next-generation, cutting-edge — unless the technology itself is the product, say what it does.
• Seamless, innovative, powerful — every product claims these.

Before: "An AI-powered platform revolutionizing how teams collaborate." After: "Meeting notes that update your CRM automatically."

Fitting each limit

The same company, written to each common limit:

• 50 characters (YC): "Payroll for restaurants in Mexico"
• 100 characters (a16z speedrun): "Payroll and tax filing for restaurants in Mexico, run from WhatsApp in minutes."
• 140 characters (SOSV): "Payroll, tax filing and tip-splitting for restaurants in Mexico, run from WhatsApp. 300 restaurants pay staff with us every week."
• 280 characters (Alchemist): add the customer's pain, your traction and why now.

Write the longest version first, then cut. It's easier to remove words than to compress an idea from scratch. Every program page in our directory lists its questions with their exact limits.

How to test your one-liner

1. The stranger test. Read it to someone outside your industry. Ask them what the company does. If they hesitate, rewrite.
2. The swap test. Replace your company name with a competitor's. If the line still works, it's not specific enough.
3. The question test. If the reader's first question is "What do you mean by…?", that word needs replacing.

One-liner examples by industry

• Fintech: "Corporate cards for construction companies."
• Health: "Remote physiotherapy for knee-replacement patients."
• Developer tools: "Integration tests that write and fix themselves."
• Climate: "Heat pumps installed in a day, financed monthly."
• Marketplaces: "On-demand welders for shipyards."

Common one-liner mistakes

• Describing the technology instead of the product. "A transformer-based retrieval system" — for whom, doing what?
• Listing several products. If you need "and" twice, pick the one your first customers pay for.
• Leaving out the customer. "Scheduling software" is a category; "scheduling software for home-care agencies" is a company.
• Borrowing a vague analogy. "Uber for X" only works if X really is on-demand, two-sided and real-time.
• Writing for investors instead of customers. The best one-liners would also work as your website headline.

From one-liner to every other answer

Once your one-liner is right, it anchors the rest of the application:

• The problem answer explains why the customer in your one-liner needs it.
• The traction answer proves that customer is using it.
• The market answer counts how many of those customers exist.
• The competition answer names what that customer uses today.

If an answer can't be connected back to your one-liner, either the answer or the one-liner needs work.

Why it matters beyond applications

Your one-liner becomes your website headline, your investor email subject line and your introduction at every event. Founders who can't write one usually haven't decided who their first customer is — so the exercise is worth doing for its own sake.

Once you have it, the rest of your application gets easier. Read how to apply to Y Combinator for how it fits into a full application — or let Applyseed adapt it to every program's limit for you.