Profitlee's answer:

Next.js 16 (App Router) and React 19 with TypeScript, styled with Tailwind CSS v4. Postgres (Neon serverless) via Drizzle ORM, authentication with Auth.js (NextAuth v5), billing through Lemon Squeezy, transactional email via Resend + React Email, PDF export with react-pdf, and internationalization via next-intl. Tested with Vitest and deployed on Vercel.

RepDB's answer

RepDB grew out of a consumer workout app its creator was building solo. Sourcing exercise images and data meant either paying for a subscription API with usage caps and no caching rights, or producing everything from scratch. The illustrated, multi-language dataset was built for us first, then split out as its own product once it became clear other indie developers had the same problem and preferred to buy the data outright rather than rent it through an API.

Profitlee's answer:

It started as the messy spreadsheet I kept rebuilding for every product I evaluated. "Sale price minus product cost" was never the real margin — referral fees, the FBA fulfillment tier, the fuel surcharge, VAT on EU marketplaces, ad spend, and returns all quietly ate into it, and I usually only saw the true number after the inventory had already landed. So I turned the spreadsheet into a proper tool with accurate, country-specific fee logic and made it auditable against each marketplace's official schedule. Profitlee is the result — an independent, solo-built calculator (not affiliated with Amazon or TikTok).

RepDB's answer

Most alternatives are subscription APIs — you pay monthly, you're capped on requests, and ExerciseDB's terms of use explicitly forbid caching or storing the data at all, so every image render is a live paid API call. RepDB is the opposite: pay once, download the files, self-host with zero ongoing dependency. It's also the only option offering true DE/ES localization and transparent images instead of a white box behind every exercise.

Profitlee's answer:

Accuracy you can verify. Profitlee breaks the full cost stack out line by line and its outputs have been cross-checked against Helium 10 and Amazon's live fees down to the cent. It's multi-marketplace (US/DE/JP + TikTok Shop) and multi-mode (FBA, FBM, Fulfilled-by-TikTok, self-fulfilled) in one tool, the core calculator is free to use with no signup, and a per-unit calculation instantly scales into a monthly revenue/gross/net P&L. Pro stays affordable at $9.99/mo (or $99/yr) and adds saved scenarios, history, PDF export, and shareable links.

RepDB's answer

Solo developers and small teams building fitness or workout-tracking apps (iOS, Android, web) who need licensed exercise images and structured exercise data, but don't want to build their own media pipeline or depend on a rate-limited third-party API.

Profitlee's answer:

Amazon FBA/FBM and TikTok Shop sellers — from first-time and side-hustle sellers validating a product before they source inventory, to established sellers and agencies pricing new SKUs across the US, German, and Japanese marketplaces. Anyone who needs to know their true net margin before committing to inventory.

RepDB's answer

RepDB is sold as a one-time download, not a metered API — you own the JSON/SQLite data and WebP images outright, with no rate limits, no per-request billing, and no risk of the vendor cutting off access. It's also the only dataset in this space with EN/DE/ES translations, transparent (alpha-channel) images with no watermark, muscle-group highlighting, safety/goal tags, and looping animations on the higher tier.

Profitlee's answer:

Profitlee is a country-accurate profit calculator: instead of one generic "fee" estimate, it uses real, separately-maintained 2026 fee tables for Amazon US, Germany, and Japan plus TikTok Shop — including size tiers, referral categories, the 3.5% fuel surcharge, inbound placement, and storage. It's VAT-aware on the EU/JP marketplaces and models the costs most calculators skip: ad spend as ACOS or TACOS, and return losses (refund administration fee + unsellable write-offs), not just marketplace fees. Every fee links back to the marketplace's own published schedule, so any number is auditable.

Profitlee's answer:

Profitlee is newly launched and used by independent Amazon FBA and TikTok Shop sellers across the US, EU, and Japan marketplaces.