If you’re building a fitness app in React Native, chances are you’ve already found react-native-body-highlighter. It’s the default answer on Stack Overflow, it’s MIT licensed, and it does what it says: highlight human body parts with SVG. If you’re searching for alternatives, you’ve probably hit one of its walls. This post walks through what those walls are, which free alternatives just move the wall somewhere else, and when it makes sense to switch approaches entirely.
Full disclosure up front: we sell an interactive Rive-based muscle heatmap at Fitness Visuals, so we’re one of the alternatives. But we also ship a fitness app ourselves, and the free SVG approach is genuinely the right call for plenty of apps. The goal here is to help you figure out which camp you’re in.
What react-native-body-highlighter does well
Credit where due, because there’s a lot to like. It’s free and MIT licensed. It’s Expo compatible. It ships male and female body models with front and back views. You pass a data array of body-part slugs with intensity values, wire up onBodyPartPress for taps, and you have a working muscle map in an afternoon:
import Body from "react-native-body-highlighter";
<Body
data={[
{ slug: "chest", intensity: 1 },
{ slug: "biceps", intensity: 2, side: "left" },
]}
gender="female"
side="front"
onBodyPartPress={(part) => console.log(part.slug)}
/>For a workout logger that wants to show “you trained chest today” with a colored region, this is enough. If that’s your whole requirement, stop reading, install it, and ship. It has roughly 270 GitHub stars and years of production use behind it.
The walls you eventually hit
Everything is a snap, nothing is a transition.The library renders static SVG polygons. When the highlighted set changes, colors swap instantly. There are no animated transitions between states, no pulse on selection, no smooth intensity ramps. For a polished 2026 fitness app, that snap is the visual difference between “template app” and “product someone designed.”
Intensity is an array index, not a value.Intensity maps to positions in a fixed color array (the default is two shades of blue). You can pass more colors, but you’re still picking from discrete buckets. There’s no notion of a continuous 0-to-1 activation level, which is what you actually have when you compute muscle load from training volume.
Regions, not muscles.The models expose around 25 broad body parts. That’s fine for “chest and arms day,” but if your programming distinguishes teres major from lats, or brachialis from biceps, the model can’t draw what your data knows.
It ends at React Native.The day you add a companion web dashboard, a watch app, or a Flutter rewrite, the highlighter doesn’t come with you. There are sibling ports (more on those below), but each is a separate codebase with separate models, separate slugs, and separate quirks. Your muscle visualization becomes N implementations that drift apart.
Flat visual fidelity. SVG polygons with fill colors look like a diagram. That can be a deliberate aesthetic, but it caps how premium the feature can feel, and the visual bar for fitness apps keeps rising.
The free alternatives (and the wall they share)
- react-body-highlighter , the React web port of the same idea, using the same SVG polygon approach.
- Muscle-Map for React Native , a newer port of a SwiftUI library with tap support and heatmap coloring.
- bodyheatmap , the Flutter equivalent, if your search brought you here from the Flutter side.
These are all reasonable libraries, and all of them share the same architecture: static SVG shapes, per-platform implementations, discrete color buckets. Switching between them trades one set of region slugs for another. None of them changes the ceiling.
The different approach: the asset is the state machine
The alternative isn’t a better SVG library, it’s moving the interactivity into the asset itself. Our heatmap is built in Rive, which means the body model ships as a single .riv file containing its own state machine. Muscles animate smoothly between states instead of snapping. Intensity tiers are runtime inputs. On the advanced version, you set four highlight colors at runtime to match your theme, and tapping any muscle emits its name and group back to your code, so tap-to-identify works out of the box.
Because the runtime does the work, the same file renders identically in Flutter, SwiftUI, native Android, and React, and it loads in React Native through Rive’s official rive-react-nativeruntime. One asset, every platform, no drift. The integration surface stays small; here’s the entire Flutter call from our open-source wrapper:
AnatomyHeatmap(
activeMuscles: {Muscle.pectoralisMajor, Muscle.biceps, Muscle.teresMajor},
)You don’t have to take the claim on faith. The basic version is free: the Flutter integration is open source on GitHub, and there’s an interactive playground where you can tap muscles in your browser without installing anything. The paid packs ($30 basic, $50 advanced, one-time with a lifetime license) add the female body shape, intensity tiers, runtime theming, tap-to-identify, and production integration samples.
How to decide
- Static highlights on broad regions are enough? Stay with react-native-body-highlighter. It’s free, proven, and an afternoon of work.
- Same feature, but on web or Flutter? Use its sibling ports above, with the caveat that you now maintain one implementation per platform.
- Animated transitions, individual muscles, runtime theming, or tap-to-identify? That’s past what static SVG was built for. Either budget the weeks to build a Rive or Skia component yourself, or buy ours and have it running today.
- Shipping on multiple platforms? A single runtime asset beats parallel SVG libraries the moment platform number two appears on your roadmap.
The honest summary: react-native-body-highlighter earned its spot as the default, and for simple use cases it should stay your pick. The reason to move on isn’t that it’s bad, it’s that muscle visualization stops being a diagram and starts being a product feature, and at that point you want an asset that behaves like one. Try the playground and judge the difference yourself.