Firefox has an offline translation feature. You can translate web pages or arbitrary text by entering “about:translations” in the address bar. Maybe someone can confirm if this works in Fennec too?

Thinking a bit outside the box, if your phone is capable of it, you could find a way to run a small local LLM on it. Maybe it can even be done in Termux?

If that’s not an option and/or you need a bigger, more capable model, you could host a local Ollama instance, and connect to it from the Ollama (IzzyOnDroid) or GPTMobile (F-Droid). This way you will only connect to yourself instead of some 3rd party translation or LLM provider.

I think that, with a well-written system prompt, you could make it more efficient by concisely instructing it to expect your text input and a language (or include permanent language instructions in system prompt), to then only output the translated version of your input in that language. This will keep the number of input+output tokens low, thereby saving some inference. You can also get creative and instruct it to output multiple variations, change the style/tone/formatting, provide an example sentence containing a single translated word, etc…

@Achyu
What’s so bad about using an online translation?
With “Translate You” you even have the option of selecting the service.

Have you tried using the futo keyboard app?

Supposedly does everything offline locally.