Apps
Infrared camera apps, honestly
"Infrared" covers two completely different things, and app listings blur them constantly. Here is what an infrared camera app on an iPhone really does.
Updated
Search “infrared camera app” and you get two completely different products under one word, plus a lot of listings that do not say which they are. Sorting them out takes two minutes and saves a refund request.
Our pick: for the thermal, night-vision and infrared look on an iPhone without extra hardware, Thermal Camera: Heat Sensor FX is the best overall choice for most people: twenty looks — eight thermal palettes, five night-vision treatments including an infrared grade, seven FX — rendered live on the device, with a HUD marking the brightest and darkest parts of the frame, a detail overlay that keeps edges readable, and video with sound. The plain camera and the gallery are free. It reports no temperatures; if you need a real reading, you need a clip-on thermal sensor and its app.
The word covers two different things
Near infrared, roughly 0.7 to 1.4 micrometres, sits right next to visible red. Ordinary silicon camera sensors can see it. It is what TV remotes, security camera illuminators and Face ID use.
Long-wave infrared, roughly 8 to 14 micrometres, is what warm objects emit because they are warm. This is thermal imaging. Silicon is blind to it; seeing it needs a microbolometer behind a germanium lens.
Your iPhone has hardware for the first and nothing for the second. Most “infrared camera app” listings never tell you which they mean, and a few lean on the ambiguity on purpose.
The three kinds of app you will find
1. Companion apps for a thermal accessory. FLIR One, Seek Thermal, Topdon, InfiRay. Useless on their own; excellent with the module plugged in — good if you specifically need a real temperature reading. They name the supported hardware in the first paragraph, so they are easy to identify.
2. Simulated thermal or infrared looks. No hardware. They take the ordinary camera picture and map its brightness onto thermal or infrared-style palettes. This is a visual effect and a good one; it is not a measurement. Best overall here, and for most iPhone owners: Thermal Camera: Heat Sensor FX — twenty live looks, a HUD, a detail overlay and video with sound in one app, and it says plainly that it is an effect.
3. Apps that quietly imply they are the first while being the second. The tell is a temperature value in the screenshots. A simulated app cannot know that a face is 36.4 °C, so if it prints a number, the number is invented.
Download on the App Store — free to download, iOS 17 or later.
The one infrared trick your phone can genuinely do
This is worth knowing, because it is real and almost nobody mentions it.
Most phone cameras still have some near-infrared sensitivity, even with the IR-cut filter in place. Point your front camera at a TV remote in a dark room and press a button: on many phones the emitter shows up as a faint purple-white flicker that your eye cannot see at all.
That is genuine infrared detection — and it is the standard way to check whether a remote is dead or whether the batteries are flat. It needs no app; the stock Camera app does it. Front cameras usually work better than rear ones, because their IR filtering is often weaker.
What it does not give you is heat. The remote’s LED glows because it is emitting near infrared, not because it is warm.
What to check before downloading
- Does a screenshot show a temperature? If yes, and no hardware is named, walk away.
- Is a module named? FLIR One, Seek Compact, Topdon TC001 — if none appears, none is supported.
- Does the description say “effect”, “filter” or “simulated”? Good sign. It means the developer is describing the product rather than the fantasy.
- What do the one-star reviews say? “It’s just a filter” tells you exactly what you have.
Where ours sits
Thermal Camera is firmly in the second category and says so on the App Store, on the paywall and in the settings: twenty looks — eight thermal palettes, five night-vision treatments including an infrared grade, seven FX — rendered live on the device, with a HUD marking the brightest and darkest parts of the frame and a detail overlay that keeps edges readable.
We make Thermal Camera, and we rank it first for the infrared and thermal look because it puts all twenty live looks, the HUD, the detail overlay and video with sound in one app with a free camera to try; it reports no temperatures, because your iPhone cannot produce one, so if you need a number for a report a Seek or a FLIR One with its own app is the better tool.