Do I need to build an MVP to validate a SaaS idea?

No — and building one first is the classic mistake. An MVP tests whether you can build the thing; validation tests whether anyone wants it, and you can answer that with forum research, problem interviews, and a landing page with a waitlist, all free. If strangers won't give you an email for the promise, they won't pay for the product. Build after the evidence shows up, not before.

What should I ask in a problem interview?

Ask about their current behavior and past attempts, never about your idea. Good questions: 'Walk me through the last time this problem hit you.' 'What did you do about it?' 'What have you already tried or paid for?' 'What happened?' Avoid 'would you use a tool that…' — people say yes to be nice, and that yes is worthless. Past behavior is evidence; hypothetical enthusiasm is not.

How many waitlist signups mean my idea is validated?

There's no magic number, and anyone selling you one is guessing. What matters is the rate (signups per real visitor from a genuine channel) and the rung of evidence. A waitlist email is the second-weakest rung — better than compliments, far weaker than a booked call or a pre-order. Treat signups as permission to climb the ladder, not as a green light to spend six months building.

Is it dishonest to make a landing page for a product that doesn't exist yet?

Not if you're transparent. Say clearly that it's upcoming — 'launching soon, join the waitlist' — and collect an email, nothing more. What crosses the line is a fake 'Buy now' flow that takes card details for something that doesn't exist. You're testing whether the promise pulls; you don't need to deceive anyone to measure that.

How to Validate a SaaS Idea With No Money

The usual way a SaaS idea dies is after months of building — when one week of checking would have killed it for free. That order is backwards, and fixing it costs nothing. Validation isn’t a budget problem — every tool you need has a free tier. It’s a courage problem: you have to show the idea to strangers before it’s real, and accept what they do (not what they say) as the verdict.

Here’s the whole playbook at $0, in the order I’d run it.

What validation actually means

Validation is evidence that strangers want the thing enough to give you something: an email, a slot on their calendar, or money. Not your friends. Not people being polite. Strangers, giving something up.

Y Combinator’s motto is “make something people want” — and the only way to know people want it is to watch what they do when you put the promise in front of them. Everything below is a way of generating that behavior cheaply.

Two rules before anything else:

Compliments are not data. “That’s a cool idea” costs the speaker nothing and predicts nothing.
You are not the customer. Even if you have the problem yourself, you’re testing whether other people have it badly enough to act.

The ladder of evidence

Every validation signal sits on a rung. Weakest to strongest:

People say it’s interesting. Nearly worthless. Everyone says this about everything.
People give an email for a waitlist. A small real cost. Worth something.
People book and show up to a 15-minute call. Time is expensive. This is serious interest.
People pre-order or sign a letter of intent. Money or a signature. This is the top.

The whole game is climbing this ladder before you write code. Distrust the bottom rung completely, treat the second rung as a hint, and don’t commit months of your life to anything that hasn’t touched rung three or four.

Step 1: Find the complaint before you pitch the cure ($0)

Before you talk to anyone, go read what people already say when nobody’s pitching them. Search Reddit and niche forums for the problem — not your product, the problem. Look for phrases like “how do you deal with,” “is there a tool for,” “I’m so sick of.”

You’re reading, not posting. Do not spam communities with your idea — that burns the channel you’ll need later. What you want from this step:

The exact words people use to describe the pain (this becomes your landing page headline).
What they currently do about it — spreadsheets, duct-taped tools, paying a VA, nothing.
Whether the complaint shows up repeatedly or you had to dig for one thread from three years ago.

If you can’t find anyone complaining, that’s your first data point, and it’s not a good one.

Step 2: Run 5-10 problem interviews

Find 5-10 people who plausibly have the problem and get them talking. The one rule that makes or breaks this: ask about their current behavior and past attempts, never about your idea.

“Would you use a tool that does X?” gets you a polite yes and zero information. People say yes to be nice. Instead:

“Walk me through the last time this happened.”
“What did you do about it?”
“What have you tried before? What did you pay for it?”
“What happened after that?”

Past behavior is evidence. If they’ve never tried to solve the problem — never searched for a tool, never hacked a spreadsheet, never paid anyone — the pain probably isn’t real enough to sustain a product, no matter how enthusiastically they nod.

Reaching out cold is the uncomfortable part, and it’s also free. A short, honest message — “I’m researching how people handle X, can I ask you three questions?” — outperforms anything clever. If writing that outreach note is what’s stopping you, the same structure I use in the professional email prompt guide works for this: context, one clear ask, easy out.

Step 3: Put up a landing page and a waitlist ($0)

Now turn the language from steps 1 and 2 into a one-page test:

One sentence stating the promise. Use the words your interviewees used, not your clever positioning.
One CTA. Join the waitlist. That’s it — no nav, no feature grid, no pricing page.
Total transparency. Say it’s upcoming. No fake “Buy now” button that takes card details for a product that doesn’t exist. You’re measuring pull, not tricking people.

The free stack: Carrd has a free tier that handles a one-page site fine, or throw plain HTML on any free subdomain you already have access to. For the form, Google Forms is free forever, and Tally’s free tier embeds cleanly if you want it to look less like a survey. Wire the CTA to the form, and you have a functioning validation machine for exactly $0.

Step 4: Drive small, genuine traffic and measure

A landing page with no visitors measures nothing. But you don’t need an ad budget — you need a handful of real humans from communities you actually belong to. Share it where you already participate, framed honestly: “I’m exploring this, does it resonate?” A few dozen genuine visitors tell you more than a thousand bought clicks, because you know exactly who they are and why they came.

Watch one number: signup rate — emails collected per real visitor. Don’t obsess over the absolute count; obsess over whether people who have the problem convert when they see the promise stated in their own words.

Then climb. Email the waitlist and ask for a 15-minute call (rung three). On the calls, if the pain is real, ask the money question: “If I build this, would you pre-pay for the first month?” or, for anything B2B-shaped, “would you sign a letter of intent?” (rung four). Every rung people climb willingly is evidence. Every rung they refuse is also evidence.

Set your kill criteria before you start

This is the step everyone skips, and it’s the one that protects the only capital you actually have: your time.

Before you run any of the above, write down what result means “drop it.” For example: if after a week of genuine effort I can’t find 10 people who care enough to give an email or take a call, this idea is dead. Whatever your line is, set it while you’re still objective — because after two weeks of effort, sunk cost will happily move the goalposts for you.

A killed idea after one week is a win. The same idea killed after six months of building is the disaster this whole process exists to prevent.

The broke-builder edge: let AI do the grunt work

Here’s what’s changed about this playbook: the mechanical parts now take minutes instead of days. An AI agent will draft your landing page copy, your survey questions, your outreach messages, and five headline variants to test — faster than you can make coffee. If you’re setting up agents to do that kind of drafting reliably, the structure matters more than the model; that’s exactly what how to write a system prompt for an AI agent covers. And the quality of what comes back tracks the quality of what you feed in — Meta-Prompt Architect is the tool I built for turning a rough “draft my landing copy” into a reusable, high-signal instruction, so the agent’s first pass is usable instead of generic.

I run my own drafting and build agents through Claude Code pointed at the z.ai GLM Coding Plan, which keeps the token bill near zero — the setup is in how to set up Claude Code with the GLM API. Full disclosure: https://z.ai/subscribe?ic=BWTG6TRYYQ is a referral link — it helps fund our compute, and it’s the same plan you’d get anyway, just through our link.

But be clear-eyed about what AI does and doesn’t buy you here. It compresses the cheap parts. The scarce input in validation was never the code or the copy — it’s honest contact with strangers. No agent can sit through a problem interview for you, and no model can make a stranger hand over an email they don’t want to give. That part is still yours, and it’s the part that counts.

Where this fits

The whole sequence — complaints → interviews → landing page → traffic → calls → money — runs on Google Forms, Carrd or a free subdomain, Tally, Reddit search, and your own nerve. Zero dollars, one to two weeks, and at the end you either have strangers’ emails and booked calls, or you have a clean kill and your next idea.

Since the building itself is nearly free now too (cheap tokens, see the GLM setup guide — referral link above, disclosed), the temptation is to skip validation entirely because “I can just build it in a weekend.” Resist that. Cheap building makes validation more valuable, not less: when everyone can ship, the only edge left is knowing what’s worth shipping. Climb the ladder first.