Wiring authentication properly takes most teams the better part of a week. Add Stripe integration, subscription management, webhook handling, and a billing portal and you are into multiple weeks before writing a line of your actual product. That is why the first decision most SaaS founders face is not whether to build auth and billing, but which shortcut to buy.
There are two kinds of shortcut. A starter kit gives you source code. A backend gives you a service. They solve the same problem in opposite ways, and the difference matters more than the price tag.
The job both categories serve
Every SaaS product needs three things before it can charge a single user: a way to verify who they are, a way to take their money, and a way to manage what they are allowed to do. None of these are your product. They are the plumbing your product sits on top of.
Building that plumbing from scratch is a known time sink. Every published estimate assumes you get it right on the first attempt, which most people do not. Billing adds another layer: Stripe's API is extensive, webhook handling has failure modes, and subscription state gets out of sync in ways that surface at the worst moments.
Starter kits and backends both exist to skip this. They just skip it in entirely different ways.
What the leading kits ship and cost
A starter kit is a codebase. You buy it, clone it, and it becomes your repository. The auth is already wired. The Stripe integration is already there. You start building features on top of a working baseline.
The leading options cover most stacks, though pricing has moved in 2026.
ShipFast targets solo founders launching B2C products quickly. It ships Next.js, Stripe or Lemon Squeezy, and NextAuth with Google sign-in and magic links. List price is $299, currently discounted to $199 for the tail end of a launch promotion. It is deliberately minimal: no multi-tenancy, no role-based access control, no test suite.
Makerkit goes further for B2B, adding team accounts, database-level permissions, and per-account billing. Pro is $349, Team is $649, both one-time. There is also a free MIT-licensed lite version without billing or teams.
supastarter covers similar B2B ground across Next.js, Nuxt, and TanStack Start, at €349 Solo, €799 Startup, and €1,499 Agency. It ships an AGENTS.md file tuned for agentic tools like Cursor and Claude Code, which its own FAQ positions as a headline feature. That detail is worth noting. It reflects where the tooling is going: the expectation that AI agents will be reading and modifying your codebase from day one.
SaaS Pegasus serves the Django world, which has historically had fewer options. Its free open-source tier covers auth and dev tooling only. Stripe subscriptions and teams start at the $449 Professional tier.
Next.js SaaS Starter is free under the MIT licence and published under the official Next.js GitHub organisation. Its README calls it intentionally minimal and a learning resource rather than a production foundation, which is worth taking at face value.
Vendors and comparison sites put the time saved somewhere between fifteen and forty hours, though none of those estimates come from a study you can check. Take them as directional. What is checkable is the spread: at $199 to $649 for the Next.js kits and $449 for Pegasus, a kit pays for itself if it saves you a day or two at a professional rate. That part is not really in dispute.
What all of the paid options share: you own the code completely. Every line is yours to read, modify, and ship.
What a backend replaces instead
A backend service takes a different position. Instead of giving you code to own, it gives you an API to call. You do not get a repository. You get endpoints.
The practical difference is maintenance. When a kit ships auth code, that code becomes your responsibility. When a backend ships auth, it remains the vendor's responsibility. You get the output without the upkeep.
The trade goes in both directions. A backend that handles auth and billing means you never patch an auth vulnerability, never update a Stripe client library, never debug a webhook that stopped firing after a dependency upgrade. That is genuinely valuable. It also means you cannot modify the underlying behaviour. You work within the API surface the vendor exposes.
One concrete example of the asymmetry: merchant of record and tax handling. No kit ships this, because no kit can. Handling tax as a merchant of record means the vendor becomes the seller in the transaction. The customer licenses their product to the vendor as a non-exclusive reseller, and the vendor then sells to the end user in its own name, taking on the legal obligation to collect and remit VAT, GST, and sales tax. That is a financial and legal infrastructure commitment that cannot be bundled into a codebase you buy once. A backend service built around this, like tiun, ships it as a core feature. For founders selling internationally, that removes a standing operational job. Registering, collecting, and filing across every jurisdiction you sell into is real work if you own it yourself.
The other side of that ledger is worth stating plainly. B2B-tier kits like Makerkit, supastarter, and Pegasus Professional ship organisations, role-based access control, and social login. Cheaper single-tenant kits mostly do not. Backends vary just as widely, and tiun sits at the narrow end of that range: its auth is one-time-passcode only, with no social login, no SSO, and no organisations or roles. If you are building for teams, that is a gap you close yourself or a reason to look elsewhere. Polar and Lemon Squeezy are the closest comparisons on the merchant of record side and are worth pricing against tiun directly before committing.
The trade-off nobody states
The marketing around starter kits implies that buying one means you are done with the infrastructure problem. You are not.
A kit gives you a snapshot of working code at a point in time. The world keeps moving. Your codebase does not update itself, and neither, necessarily, does the kit. ShipFast's own FAQ, at the time of writing, lists its last update as six months ago.
Eighteen months after you clone a starter kit, here is what will have changed around you:
Next.js will have released at least one major version with breaking changes. The authentication library you are using will have shipped a version that changes how sessions work. Stripe will have shipped at least one named major release with backward-incompatible changes, which you can defer but not indefinitely. New tax rules will have taken effect in at least one market you sell into. Security advisories will have flagged two or three packages in your dependency tree.
None of these are hypothetical. They are the normal pace of change in JavaScript tooling. Auth libraries in particular have a history of significant version jumps. The shift from next-auth version 3 to version 4, and then from version 4 to version 5, changed enough that migration guides had to be written for each. Each transition required real work to absorb.
You bought the kit to skip the work of building auth. You still own the work of maintaining it.
This is not an argument against kits. It is the argument that should be in every kit's README and rarely is. Whatever time savings a kit delivers is front-loaded. The maintenance cost is spread across years.
Maintenance over eighteen months: the honest breakdown
Here is what actually accumulates in the first eighteen months after launching with a starter kit.
Dependency updates. A year-old Next.js project will typically have dozens of outdated packages. Most are minor updates that take minutes. A handful involve breaking changes that take hours.
Auth library changes. If you are on next-auth, plan for at least one significant migration. The v4 to v5 jump renames adapter packages, replaces the middleware and server-side imports, and changes the session cookie prefix from next-auth.session-token to authjs.session-token, which logs every existing user out on deploy unless you write a shim. Worth knowing before you build on it: v5 has been in beta since 2023 and was still shipping as 5.0.0-beta.32 in July 2026, while npm continues to tag v4 as latest.
Stripe API versioning. Stripe pins your account to a dated version and is unusually generous about backward compatibility, so nothing breaks the day they ship. Since the acacia release, monthly versions are backward compatible and only the twice-yearly named releases carry breaking changes. The cost is deferred rather than removed: the longer you sit on an old pinned version, the larger the eventual upgrade, and new features land on newer versions only.
Tax rule changes. The EU regularly updates digital services tax thresholds. Canada and Australia have both introduced or modified GST rules for digital goods in recent years. If you are handling tax yourself through Stripe Tax or similar, each rule change requires you to verify your configuration is still correct.
Security patches. Auth systems are high-value targets. In one July 2026 cycle alone, Auth.js closed four advisories spanning its core package and both the v4 and v5 lines. If your kit ships that library, those land on you.
None of this is crushing. Experienced teams handle it as routine. But it is real work, and it compounds with everything else on your plate.
When each is the right purchase
The decision comes down to what you want to own and what you want to hand off permanently.
Buy a starter kit when:
You need deep customisation of the auth or billing flow. A kit gives you the source, which means you can modify anything. If your product requires unusual login flows, non-standard subscription structures, or billing logic that does not fit a standard model, owning the code is the right call.
Your team has the capacity to absorb ongoing maintenance. If you have engineers comfortable with JavaScript tooling and time to track upstream changes, the upkeep cost is manageable.
You need organisations, role-based access control, and social login from day one. Most B2B-tier kits ship these. Cheaper single-tenant kits and many backend services do not.
Use a backend service when:
You want auth and billing to stop being your problem entirely. Not just at launch, but in eighteen months and in three years. A service absorbs the maintenance so you never have to.
You are selling internationally and tax compliance is a real concern. Merchant of record coverage removes a category of legal and operational risk that no kit can touch.
You want to move fast and stay fast. The compounding maintenance cost of a kit is real. A service that requires no patching keeps your engineering attention on your product rather than your infrastructure.
Neither is better. They fail differently.
Starter kits and backends solve the same job in opposite ways. A kit gives you source code you own and then maintain, including every auth and billing bug for the life of the product. A backend gives you a service you do not maintain and cannot fully modify. Neither is better. They fail differently.
The question to ask before spending $200 to $650 is not which option is superior. It is which failure mode fits your situation. Owning code you cannot keep up with is one kind of problem. Depending on a service you cannot modify is another. Both are real risks. Neither disappears by choosing carefully once.
The most expensive decision in this space is choosing the wrong option and not realising it until you are eighteen months in.
Frequently asked questions
What is the difference between a SaaS starter kit and a backend service?
A SaaS starter kit is a codebase you purchase and own outright. It ships with auth, billing, and other infrastructure already wired together, and you deploy it as your own application. A backend service is an external API you call. It handles auth, billing, or both on the vendor's infrastructure. You get the output without owning the code. The core trade-off is ownership versus maintenance: a kit gives you full control and full responsibility, while a backend service limits your ability to customise in exchange for removing ongoing upkeep from your plate entirely.
Do SaaS starter kits require ongoing maintenance after purchase?
Yes. A starter kit gives you a snapshot of working code at the point of purchase. After that, the responsibility for keeping it current is yours. In the first eighteen months after launch, a typical Next.js project will accumulate outdated dependencies, at least one significant auth library change, Stripe API deprecations to track, and one or more security patches to apply. The time savings a kit delivers are front-loaded at setup. The maintenance cost is spread across the life of the product. Teams without the capacity to absorb that work should factor it into the purchase decision.
What is a merchant of record and do I need one for my SaaS?
A merchant of record is a company that takes legal responsibility for processing a sale, including collecting and remitting the applicable taxes such as VAT, GST, and US sales tax on your behalf. When a backend service operates as your merchant of record, you are not responsible for calculating, collecting, or filing taxes in each jurisdiction you sell into. No starter kit can provide this, because it is a financial and legal infrastructure commitment, not a software feature. If you sell internationally to customers across multiple tax jurisdictions, working with a merchant of record removes a significant compliance burden that would otherwise require dedicated attention as your revenue grows.
Is a SaaS starter kit worth it compared to building auth and billing from scratch?
For most founders, yes. Building authentication correctly from scratch takes forty to sixty hours at minimum, and billing integration adds significantly more time on top of that. Paid starter kits are generally estimated to save fifteen to forty hours of setup work. At a standard developer rate, that time is worth several multiples of the purchase price. The more relevant question is not whether a kit is worth buying over building from scratch, but whether a kit is the right shortcut compared to a backend service. If your team cannot absorb ongoing maintenance, or if international tax compliance is a requirement, a backend service may deliver more durable value than a one-time codebase purchase.