
RxDB
Firebase
PouchDB
GUN
SignalDB
Supabase
FeathersJS
Realm.io
RepDB
RxDB, which stands for Reactive Database, is a JavaScript-based NoSQL database designed for a wide range of applications such as websites, hybrid apps, Electron apps, progressive web apps, and Node.js. The "reactive" aspect of RxDB allows you not only to retrieve the current state of the database but also to subscribe to all changes in the state, including query results or specific fields within a document. This feature is particularly advantageous for real-time user interface applications, as it facilitates development and offers notable performance benefits. Additionally, RxDB can be utilized to build efficient backends in Node.js.
RepDB is a one-time-purchase exercise dataset for developers building fitness and workout apps โ not a subscription, not a rate-limited API. You download the data once and own it: JSON (and SQLite on the higher tier), WebP images, and full EN/DE/ES translations, with no per-request billing and no dependency on our servers staying up.
A free tier includes 400 exercises with flat-style 512ร512 images, attribution-licensed for commercial in-app use. The Starter tier ($199) adds the full catalog in classic white-background style. Standard ($399) adds transparent 1024px images, looping animations, exercise relations (similar/progressions/regressions), workout templates, and embeddings โ exclusive to that tier.
Every exercise includes muscle-group highlighting, equipment/muscle icons, MET values, and safety/goal tags. Compared to GIF- or JPG-based competitor APIs, RepDB images are transparent WebP with no watermarks, so they drop into any app UI without a white box around them.
RxDB
RepDBRepDB's answer:
RepDB is sold as a one-time download, not a metered API โ 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.
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.
RepDB's answer:
Most alternatives are subscription APIs โ 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.
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.
Based on our record, RxDB seems to be more popular. It has been mentiond 14 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
Iโm doing offline-first apps at work and want to emphasize that youโre constraining yourself a lot trying to do this. As mentioned, everything fast(ish) is using SQLite under the hood. If you donโt already know, SQLite has a limited set of types, and some funky defaults. How are you going to take this loosey-goosey typed data and store it in a backend database when you sync? What about foreign key... - Source: Hacker News / 11 months ago
> I'm thinking to give it a try in one of my React Native apps that face very uncertain connectivity. Some similar stuff you may want to investigate (no real opinion, just sharing since I've investigated this space a bit): - https://rxdb.info. - Source: Hacker News / over 1 year ago
Looks like it could be a more batteries-included/opinionated alternative to RxDB (https://rxdb.info). The relational queries might help some people who tend to think in SQL as opposed to documents (as in CouchDB or MongoDB) and the WebSockets for synchronization will help people get started more quickly. (RxDB provides interfaces for those who want to implement their own storage engine and/or synchronization... - Source: Hacker News / about 2 years ago
Some years ago "offline-first" was a thing: https://web.archive.org/web/20170720174332/http://hood.ie/initiatives/#offline-first Primarily based on PouchDB/CouchDB. Now the site redirects to RxDB. https://rxdb.info/ There's still a site by that name but I don't quite understand what's the intention https://offlinefirst.org/. - Source: Hacker News / about 2 years ago
I'm interested in this problem also! I think there is a large overlap with projects that market/focus on offline-first experiences. AFAIK this problem can be solved by: 1) Considering a client-side copy of the database that gets synced with the remote DB. This is an approach [PowerSync](https://www.powersync.com/) and [ElectricSql](https://electric-sql.com/) and [rxdb](https://rxdb.info/) take! - Source: Hacker News / over 2 years ago
Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
PouchDB - Open-source JavaScript database inspired by Apache CouchDB that's designed to run well within the browser
GUN - Self-hosted Firebase.
SignalDB - SignalDB is a reactive, local-first JavaScript database designed for modern web applications. It combines signal-based reactivity with powerful local data management and real-time synchronization capabilities.
Supabase - An open source Firebase alternative
FeathersJS - Wow your users. Build incredible real-time applications in record time.