COLLECTION · 10 APPS

The Hardest SaaS Apps to Build Yourself

Every app here still gets a real, specific reason on its own page — a rendering engine, a licensing problem, a compliance surface — not just "it's hard." Worth reading even if you're not building anything: knowing where the real moats are is half the judgment call.

AhrefsMarketingJust pay56Ahrefs' entire value is its backlink index — a continuously crawled map of links across the web, refreshed on a schedule most companies can't match. There's no personal-scale version of 'crawl a meaningful fraction of the internet.'

Adobe IllustratorDesignJust pay57Vector editing lives on precise path mathematics — bezier curves, boolean shape operations, and print-accurate color — refined over decades. It shares Photoshop's problem: individually explainable pieces, but the whole is a rendering engine most teams never attempt to build from scratch.

GustoFinanceJust pay64Calculating a paycheck is arithmetic. Correctly withholding and filing payroll taxes across federal, state, and sometimes local jurisdictions — and staying correct as rules change every year — is a compliance operation most companies rightly refuse to DIY.

QuickBooksFinanceJust pay64Recording transactions in a ledger is old, well-understood software. What actually justifies the subscription is staying correct against tax rules that change by jurisdiction and year, connected to your real bank accounts — get either wrong and it's your business's books or a filing, not a bug report.

Adobe PhotoshopDesignJust pay67A raster image editor with layers, masks, and filters is decades of deep, specialized engineering — color management, non-destructive editing, and performance on huge files, all at once. This sits alongside Figma as one of the clearest 'don't even try' cases on the register.

SpotifyDesignJust pay67A music player with playlists is genuinely simple software. The reason nobody builds their own Spotify isn't the code — it's that you can't license a single major-label song, let alone a hundred million of them. This is a pure legal moat wearing a technical disguise.

FigmaDesignJust pay68A multiplayer vector canvas that stays in sync at 60fps across a design team is one of the hardest things shipped on the web this decade. This is what moats look like.

SEMrushMarketingJust pay69The dashboard around SEO data — keyword lists, position tracking, a UI — is buildable. The actual product is a continuously updated index of billions of keywords and search results, crawled and refreshed at a scale no solo build gets near.

1PasswordDevtoolsJust pay72This is the one category on the register where 'buildable in a weekend' is a warning label, not a recommendation. Password managers are a security product first and a CRUD app a distant second — get the cryptography wrong and you don't have a bug, you have every password you own exposed.

NordVPNDevtoolsJust pay72The VPN protocol itself is open and well-documented — WireGuard is genuinely simple to configure. What you're actually paying for is thousands of servers in dozens of countries, kept fast and unblocked, which is real global infrastructure, not a config file.

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