The must-have features of a modern SaaS

Authentication and account security

Email/password login, social login (Google, GitHub, Microsoft), and above all real role checks on every sensitive request — not just at initial login. A compromised account or an access revocation must take effect immediately across the whole application, not only after a session token's natural expiry, which can remain valid for several hours depending on the configuration.

Billing and subscription management

Clients need to be able to manage their own card and subscription — create, upgrade, cancel, or pause — without systematically going through support for every minor change. This self-service reduces support load while improving the client's experience, since they don't have to wait for a human reply for something as simple as changing plans.

A complete admin panel

An overview of customers, sales, usage trends, and the ability to act on a user's behalf when support needs it (with that action fully traced) — without ever relying on direct, untracked access to the production database, which is both risky and impossible to verify after the fact.

Structured customer support

A support channel that works just as well for anonymous visitors still exploring the product as for already logged-in clients, with a browsable history of past exchanges and clear categorization of requests by topic, to prioritize correctly and spot recurring issues.

Compliance that's actually tracked, not just displayed

Versioned terms of service with precise per-user acceptance traceability, and real cookie consent logged in the database — not just a cosmetic banner that disappears for good on the first click with no verifiable trace in case of an audit.

Marketing content that evolves without a technical redeploy

Being able to publish a new page or blog article without depending on a full technical deployment cycle is a capability often underestimated at launch, but critical as soon as the marketing team grows. Content and code don't need to move at the same pace, and forcing them to creates an unnecessary bottleneck on the technical team.

Observability and an audit log

Knowing precisely what happened in the system, by whom, and when — not just for technical debugging, but also to answer a client question or meet a compliance obligation. A centralized audit log, browsable without deep technical expertise, turns an uncertain investigation into a fast factual check.

Multi-tenancy as soon as B2B comes into play

As soon as a client can invite several colleagues under one account, strict data isolation between client organizations stops being an implementation detail and becomes a fundamental security requirement, covered in more depth in the dedicated article in this series.

Prioritizing without building everything at once

None of these features need to be perfect on day one, but they all need to exist in at least a minimal form before your first real paying client — a B2B client, in particular, immediately notices the absence of a working admin panel or a clear privacy policy, and that directly weighs on their decision to sign or not.

What a B2B client checks first

In the order most commonly observed during B2B evaluations: authentication security and role management, billing clarity and cancellation terms, and only then the product's specific business features. A SaaS that neglects the first three in favor of one brilliant differentiating feature often loses sales for reasons that have nothing to do with the quality of the core product.

That's precisely why these features, though rarely visible in a sales demo, deserve to be solid from the very first client — they almost never get noticed when they work well, but they're noticed immediately when they're missing.