How to vet a dev agency before you sign anything

Yes, we're an agency writing a guide on vetting agencies. Read it adversarially — every test here is one you can and should run on us. That's rather the point: a good vendor survives this checklist, and a bad one gets visibly uncomfortable by question three.

The bait-and-switch you're actually protecting against

The most common way agency projects go wrong isn't fraud — it's the sales-to-junior handoff. An impressive senior engineer runs your calls, answers your architecture questions, wins your trust. You sign. Your code is then written by two juniors you've never met, with the senior "supervising" across nine other accounts. You discover this three months in, via the codebase.

Almost every question below is a probe for this one failure mode.

Questions to ask on the first call

"Who exactly will write the code, and can I meet them before signing?" The only acceptable answer is names and a call. "We'll assign the best-fit team from our talent pool" means the people in front of you are not the people you're buying.
"Walk me through a project that went badly." Every real agency has one. A candid answer about a blown estimate or a fired client tells you how they behave under pressure. "We've never really had one" ends the conversation.
"What would you cut from my spec?" Strong teams push back on scope — it's the most senior skill there is. If they nod along with all 40 features and quote a price, they're pricing your budget, not your project.
"What happens if you miss the deadline?" You're listening for whether consequences exist at all: a guarantee, a penalty, free overrun. Anyone unwilling to attach any consequence to their own estimate is telling you its confidence level.
"Show me a pull request from a current project." (Anonymized is fine.) You'll learn more from one diff and its review comments than from their entire portfolio page.

Red flags, in rough order of severity

You can't meet the engineers. See above. This is the big one.
A detailed quote appears within hours of a vague brief. Real estimation requires questions. Instant precision means a sales formula: your perceived budget times a coefficient.
Everything is possible, nothing is a problem. Competence sounds like "yes, but here's the trade-off." Salesmanship sounds like "absolutely, easy."
The portfolio is screenshots, not products. Ask for URLs. Click them. Sign up. You'd be amazed how many showcase items are dead, broken, or someone else's template.
References are offered but somehow never materialize. Chase two, and actually call them. Ask each one only this: "Would you hire them again for the next project?" The pause tells you everything.
Contract silence on IP and source access. You should own the code and hold repo access from week one — not receive a zip file at final payment. Code held hostage is a business model.

What real proof looks like

Marketing claims are free; these are expensive to fake:

Working products with real users — things you can log into today, not case-study PDFs.
Repo access during the project, weekly demos of running software. Not status decks. Software.
Public technical footprint. Engineers who teach, write, or maintain open source are auditable. Thousands of students or readers are thousands of people who'd notice if they were frauds.
Published prices. An agency that puts numbers on its site has committed to defending them. "Contact us for pricing" often means "we price by what you look like you can spend."
A willingness to say no on the first call. The strongest signal in this whole list. A vendor who talks you out of scope — or out of building at all — is optimizing for the relationship, not the invoice.

The one-week test

Still unsure after all that? Buy a small paid discovery or a one-week starter task — a real deliverable, fixed price, $1–3k. You'll learn more about communication, honesty, and code quality in that week than in any number of sales calls. Any agency confident in its own work will take that deal. Be suspicious of one that will only sell you the whole project.

If you're vetting teams for a project right now, book a 30-minute call — run this checklist on us, and we'll give you straight answers, including which questions we think you should also ask our competitors.