Someday soon when traveling to a foreign country where you don’t speak the language, understanding locals may be as easy as pulling on a pair of augmented-reality glasses. Last month, Googledemonstrated developing translation technology the company calls “subtitles for the world.” Google’s prototype spectacles project translated speech into a wearer’s field of vision in real time using AR technology.

While it’s probably a ways off before travelers will be able to secure a pair of Google’s glasses—the company hasn’t said when the product might be available—translation technology has already made some notable gains in recent years, making foreign travel more manageable. We’ve sifted through the most promising smartphone apps designed to help travelers break the language barrier.

Translating on the Go

When it comes to quick and effective translation, Google Translate is perhaps the most essential tool for travelers needing to decipher communications when they don’t speak the language in their chosen destination. Yes, social media users have poked plenty of fun at the service online for sometimes rendering awkward or inaccurate translations. (Google translates hamsterkauf, the German word for “panic buying” into “hamster purchase” in English.) However despite the occasional linguistic slips, Google Translate is a powerful tool that has matured significantly since launching in 2006.

The app, which supports 133 languages, is especially useful for travelers consistently racking up new passport stamps. “I traveled to 19 different countries and I used Google Translate in all of them,” said Isabelle Lieblein, a 22-year-old American who, while living in Europe last year, set out to visit as many countries as possible.

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Ms. Lieblein, who shares travel tips on TikTok, used Google’s camera function to translate written text like signs and restaurant menus. She also appreciated that Google Translate allows for downloading languages pre-arrival. That way, the app works offline.

Like many travelers, Ms. Lieblein said that for more complicated conversations and text, she found that a rival app called DeepL, which uses artificial intelligence, sometimes produced more refined translations than Google. Based in Germany, DeepL says its service is more than three times more accurate than its closest competitors. Basic DeepL is free but requires an internet connection to function.

Talk the Talk

Travelers eager to pick up the local language before they arrive or while they’re traveling can find dozens of available smartphone apps. The clear leader is Duolingo, a playful app which delivers bite-size lessons on an animated platform akin to popular mobile games. According to research firm Sensor Tower Inc., since 2019 Duolingo has led all other language apps world-wide in terms of revenue and downloads. Duolingo offers both a free ad-supported service and a premium ad-free version for $12.99 a month. As of 2021, the app taught 40 languages.

Rosetta Stone, a longtime purveyor of language-learning software, also has a smartphone subscription service which costs $44.99 for three months. The subscription includes a “Phrasebook” feature for travelers anxious to focus on common phrases.

“Linguado, a ‘social version’ of Duolingo, encourages language learners to connect with other users.”

Goal-oriented, gamified platforms appear to be favorites among consumers. Also ranking in Sensor Tower’s top-five are language apps Babbel, a flashcard based program with real photos, and Busuu, which includes a community feature that allows learners to befriend one another. However, users won’t be able to advance far with either app without paying. Babbel costs a minimum of $42.99 for three months. Premium access to Busuu runs from $10.99 a month.

But using your smartphone is only going to take you so far, said Alexander Max Kaplan, founder of Linguado, a newer app that encourages language learners to seek out and connect with other users by employing search criteria like location, nationality and languages of interest. “The number one way to learn a language is through immersion,” said Mr. Kaplan, calling his platform “a social version” of Duolingo that aims to help connect users interested in language exchange. “The only way you can immerse yourself in a language is with other humans,” he said.

Write to R.T. Watson at rt.watson@wsj.com