How we picked
There is no single best language learning app, and any list that crowns one is not paying attention. The right app depends entirely on what you are trying to do, how you like to learn, and which language you have picked. So instead of one winner, this guide ranks the apps by the job they do best - and is honest about the one thing none of them does.
We weight four things: how well it actually teaches (does it explain, or just drill?), value for money (especially on the annual plans, which is how sane people buy these), how well it suits real adult learners rather than gamified dopamine loops, and which languages it genuinely supports versus the ones it lists but half-builds.
The one thing every app gets wrong
Before the picks, the uncomfortable bit. No language learning app makes you fluent. They cannot, because fluency is built by producing the language - speaking it, badly, to someone who corrects you - and an app cannot give you that. The best apps are very good at the foundation: vocabulary, grammar, listening, the confidence to open your mouth. They are not a path to fluency, whatever the advert says.
The learners who get fluent fastest treat an app as phase one and a real tutor as phase two. Keep that in mind as you read, because it changes which app is "best" for you: if you are six months from booking your first tutor anyway, you only need an app that builds a clean foundation cheaply.
Free versus paid
If your requirement is free, the answer is Duolingo and the conversation is short. It is genuinely free, it is in your language, and it will build the daily habit that everything else depends on. You will trade away proper grammar instruction and meaningful speaking practice for that zero price - a fair deal when you are starting.
If you will pay a little, a good paid app like Babbel teaches noticeably better and is structured for real progress. But be clear about the size of the upgrade: the jump from free to paid is small next to the jump from any app to real conversation. Do not spend £100 a year on the perfect app and zero on a tutor. The ratio should be the other way round.
A note on "language learning software"
The old desktop "language learning software" category - boxed products you installed - has almost entirely become subscription apps and web platforms. The names that survived (Rosetta Stone chief among them) are now apps like the rest. So when people search for the best language learning software, the honest answer is the same as the best app: it depends on the job. The picks above are the modern equivalents of what that search used to mean.
The bottom line
Start with Babbel if you want structure and a European language, Pimsleur if you want to speak and listen on the move, or Duolingo if you want free and frictionless. Then, around the six-month mark, do the thing the apps will not tell you to do: book a real tutor and start talking. That is the path. Everything above is just how to walk the first part of it cheaply.