Login and Sign-Up for Your MVP: Email, Google, Magic Links or SSO

Ship two login methods at launch, not five: email and password plus Google sign-in, with Sign in with Apple added only if you release an iOS app. In a 2026 fixed-price build, email and password with verification and reset costs about $800-$2,500, each social sign-in adds $300-$800, magic links or SMS codes add $500-$1,500, and enterprise SSO runs $3,000-$8,000 custom or $50-$125 per customer per month through a provider. The button itself is never the expensive part; the recovery paths around it are, and when a quote skips password reset, email delivery or account linking, those are the gaps that lock real users out in week one. This guide walks through what login actually includes, compares the six common methods with prices, tells you which to ship first by audience, and lists the nine mistakes we see most often in builds that reach us for repair.

What you are actually paying for when you buy "login"

A login screen is one of seven pieces, and a quote that prices only the screen will deliver a product nobody can get back into. Any complete login feature includes:

1. Sign-up and sign-in forms with validation, error messages and a loading state. The visible part, about 15 percent of the work.
2. Email verification so a stranger cannot register with your customer's address. Requires a transactional email service and a verified sending domain.
3. Password reset with a time-limited link. Skipping it is the single most common lockout cause we see.
4. Session management: how long a user stays logged in, what happens on a second device, and how a token refreshes without a surprise logout.
5. Account linking: the rule for a user who registers with Google on Monday and tries a password with the same email on Friday.
6. Logout and account deletion, which both app stores now require inside the app, not by emailing support.
7. Rate limiting and bot protection so a script cannot try 10,000 passwords or create 10,000 fake accounts overnight.

Hosted auth services such as Supabase Auth, Firebase Auth, Clerk and Auth0 handle pieces two through seven out of the box, which is why a competent studio uses one and builds the forms on top. A quote that proposes writing password hashing, reset tokens and session rotation from scratch is two to three times more expensive and is the kind of decision that lands on the expensive MVP mistakes list. The service is free at launch volumes, as the pricing section below shows.

The six login methods, compared with 2026 prices

Build costs below are what each method adds inside a fixed-price MVP that already uses a hosted auth service. Monthly costs assume about 1,000 active users and United States traffic; they scale with volume and country.

Two patterns fall out of the table. First, Google sign-in is the cheapest method with the lowest friction, which is why it belongs in almost every launch. Second, every method that depends on a message arriving (email verification, magic links, SMS codes) carries delivery risk that no amount of front-end polish fixes. If you take one method of that kind, budget for a verified sending domain and a paid email service rather than the free tier of a shared one.

Which methods to ship first, by audience

The right set depends on who signs up and how often they return, not on what looks modern. Here is what we recommend for the five audiences we build for most.

Consumer web app

Google sign-in plus email and password. Roughly 60-75 percent of consumer web sign-ups choose Google when it is offered first, and the rest want a password they control. Skip magic links at launch unless the product is used less than weekly. Expected cost inside the build: $1,100-$3,300.

Consumer mobile app (iOS and Android)

Google, Apple and email. Apple is mandatory on iOS the moment you offer Google (details in the app store section below), and Google is the default identity on Android. Keep email and password as the fallback for users who distrust both. Expected cost: $1,400-$4,100, plus the $99 per year Apple Developer account that must be in your name, not your agency's.

B2B SaaS

Email and password plus Google sign-in, with a workspace model where the first user creates the company and invites colleagues by email. Do not build SSO before someone pays for it; most companies under 200 employees accept Google sign-in for a pilot. When a customer does ask, add it through a provider at $50-$125 per connection per month and price it into an enterprise plan. The structure matters more than the method: the invite flow and role permissions in a B2B SaaS MVP usually cost more than the login itself.

Internal tool for your own company

One method only: sign-in with your company's Google Workspace or Microsoft Entra account, restricted to your email domain. No sign-up form, no password reset, no email service to configure. This is the cheapest login there is, typically $300-$800, and it removes the biggest security risk in internal tools, which is a former employee's password that nobody revoked.

Marketplace or booking app

Match the login to the side with the higher stakes. Buyers and customers get Google plus email; providers and sellers, who will log in daily and receive money, get email and password with a phone number verified by SMS code for payouts and notifications. Budget $1,600-$4,800 for both sides, and make sure one person can hold both roles under one account rather than two logins.

What the auth services cost in 2026

At MVP volume the service itself is close to free; the monthly line that matters is email or SMS delivery. Prices below are published list prices as of October 2026 and change often, so confirm before you sign.

• Supabase Auth: included with a Supabase project. Free tier covers 50,000 monthly active users; the Pro plan is $25 per month and includes 100,000. Social providers and magic links cost nothing extra; SMS goes through your own Twilio or similar account.
• Firebase Auth: free for email, Google and Apple sign-in at any volume. Phone sign-in bills per verification after a free monthly allowance, roughly $0.01-$0.06 per SMS depending on country.
• Clerk: free up to 10,000 monthly active users, then about $0.02 per additional user; the Pro plan is $25 per month. SAML SSO is an add-on at $50 per connection per month. Ships pre-built sign-in components, which cuts $300-$800 from the front-end work.
• Auth0: free up to 25,000 monthly active users; paid plans start at about $35 per month and rise quickly once you need enterprise connections or custom domains.
• WorkOS: its base sign-in is free up to one million users, and enterprise SSO is $125 per customer connection per month. The common choice when the first enterprise customer arrives.
• Transactional email (Resend, Postmark, SendGrid or similar): $0-$20 per month at launch volume. This is the line that must exist on day one if any method depends on email arriving.

Whichever service you choose, insist that user records live in your own database with the provider's user ID stored next to them. That keeps the switch to another provider a two-week job instead of a rebuild, and it is one of the items to verify in the handover checklist. The full running cost picture, with hosting and payments, is in what an MVP costs to run each month.

The nine mistakes that lock users out

These are the login failures that generate the most support emails in the first month, in roughly the order we see them. Every one is cheap to prevent and expensive to discover live.

1. No password reset at launch. About 1 in 5 users forgets a new password within 30 days. Without a reset flow, every one of them emails you, and half of them never come back. Reset is part of the feature, not a phase-two item.
2. Verification emails sent from an unverified domain. If your email service sends from a shared address without SPF, DKIM and DMARC records on your own domain, Gmail and Outlook route 20-40 percent of your verification and reset emails to spam. Your developer needs DNS access to your domain for one hour to fix this; give it before the build, not after launch.
3. Magic links that open in the wrong browser. On a phone, the email app opens the link in its own in-app browser, not the one where the user started, and the session does not carry over. Corporate email scanners also click links before the user does, consuming one-time links. Fix: include a six-digit code in the same email, allow the link to be opened in any browser, and expire it after 15 minutes, not 60 seconds.
4. Account collisions. A user signs up with Google, later types the same email with a new password, and gets either a second account or an unexplained error. Decide the rule before the build: link by verified email, and tell the user which method they used last time.
5. Google consent screen left in testing mode. A Google Cloud OAuth app in testing mode allows only 100 named test users and expires their tokens every 7 days. Users outside the list see a scary warning or a hard block. Publishing the app takes ten minutes for basic profile scopes; ask for proof it was done.
6. Google without Apple on iOS. App Review rejects the build, and you lose 2-7 days per round. The rule is spelled out in the app store section below.
7. Apple relay emails nobody can reach. Users who pick Hide My Email get an address like abc123@privaterelay.appleid.com. Your own emails to that address bounce unless your sending domain is registered in your Apple developer account. Budget one hour for it.
8. Sessions that expire too fast. A one-hour session on a mobile app means users get logged out mid-task and believe their data was lost. Thirty days with silent refresh is the normal default for consumer apps; eight hours is reasonable for tools handling money.
9. The agency owns the login accounts. The Google Cloud project with the OAuth client, the Apple Developer account, the auth service workspace and the email service all must be created under your own email. Otherwise a disagreement or a closed agency locks every user out at once. The full list is in which accounts a founder must own before the build.

What the app stores require from your login

Mobile adds three rules that web apps never meet, and each one is a rejection if missed. Plan for them in the spec rather than discovering them in review.

• Sign in with Apple is required on iOS whenever the app offers any third-party or social login such as Google, Facebook or Microsoft (App Store guideline 4.8). Exceptions exist only when your sole login is your own email and password system, or when the app is limited to a company's own employees with their enterprise login.
• In-app account deletion is required on both stores. Apple has demanded it since 2022 (guideline 5.1.1), and Google Play requires an in-app deletion path plus a web deletion link in the store listing. A support email address does not count. Budget $300-$600 for the deletion flow, including removing data from your database and the auth service.
• A demo account for reviewers. If anything sits behind login, App Review needs working credentials in the submission notes. A missing or expired demo login is one of the top three rejection reasons we see.

The rest of the review checklist, including privacy labels and screenshot rules, is in getting your MVP approved on the App Store and Google Play.

Our recommendation, and what it costs inside a SquadPrime build

For nine out of ten MVPs the answer is a hosted auth service, email and password, Google sign-in, and Apple on iOS. Login then lands at $1,100-$4,100 of a total build, which is 10-25 percent of a $10,000-$15,000 MVP budget and a smaller share of larger ones. Spend the saved money on the part that follows login, because a frictionless sign-up that leads into an empty screen is still a lost user; how to onboard your first users covers what the first five minutes after sign-up should contain.

Defer magic links, SMS codes, passkeys and SSO until you have a specific reason: usage data showing users return less than weekly, a delivery business where the phone number is the identity, or a signed enterprise customer. Each of those is a one-to-two-week addition later, not a reason to delay launch now. To see how login sits next to payments, chat, admin and AI in a full quote, run your feature list through the free MVP cost calculator, then compare line by line with what each MVP feature costs in 2026. At SquadPrime, every build is scoped to one fixed price from $4,000 by senior professionals, with a private preview link you can click by day 5, so you will see the real sign-up flow working, on your own accounts, before the first week is over.

FAQ

Which login method should an MVP launch with?

Launch with email and password plus Google sign-in, and add Sign in with Apple if you ship an iOS app. That pair covers more than 90 percent of first users, costs roughly $1,100 to $3,300 inside a fixed-price build, and leaves nothing to explain. Add magic links, SMS codes, passkeys or SSO only when your own usage data or a paying customer asks for them.

How much does login cost to build in 2026?

Inside a fixed-price MVP, email and password with verification and reset costs about $800 to $2,500, each social sign-in such as Google or Apple adds $300 to $800, magic links or SMS codes add $500 to $1,500, and enterprise SSO costs $3,000 to $8,000 custom or $500 to $1,500 through a provider plus $50 to $125 per customer connection per month. Login built from scratch with no auth service costs two to three times more and is a red flag.

Are magic links better than passwords for an MVP?

Only for products people open a few times a month. A magic link removes the sign-up form, but every return visit means opening email, and on phones the link often opens in a different browser than the one the user started in, which shows an invalid link error. For a tool used daily, email and password or Google sign-in beats magic links. If you use magic links, send a six-digit code in the same email as a fallback.

Do I need Sign in with Apple in my MVP?

Yes if your iOS app offers any third-party login such as Google, Facebook or Microsoft. Apple guideline 4.8 requires Sign in with Apple as an equivalent option in that case, and reviewers reject apps that skip it. If your app offers only your own email and password login, you are not required to add Apple. On Android and the web there is no equivalent rule.

When should my MVP support SSO with SAML?

Only when a paying customer asks for it in writing, and ideally on a plan priced to cover it. Enterprise SSO costs $3,000 to $8,000 to build custom or $50 to $125 per customer connection per month through a provider, and no customer under about 50 employees ever needs it. Ship Google sign-in and email first; most companies accept that for a pilot.

Should login be built from scratch or on an auth service?

On a service. Supabase Auth, Firebase Auth, Clerk and Auth0 all have free tiers that cover a launch, and they handle password hashing, reset flows, session rotation, rate limiting and social providers out of the box. Building those yourself costs two to three times more, takes longer, and is where security holes come from. Keep the user table in your own database so you can switch services later.

All third-party names and trademarks belong to their respective owners and are used for identification only. Any market figures reflect our experience building MVPs and typical ranges as of October 26, 2026, and may change at any time. Spotted something outdated or inaccurate? Email talk@squadprime.com and we'll correct it promptly.

Related: What each MVP feature costs in 2026 · Which accounts a founder must own before the build