Multilingual SEO: Tips for optimising a website in several languages

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Why localisation is no longer enough: the cultural issues behind multilingual SEO

Until the mid-2010s, the majority of e-tailers were content to duplicate their product sheets in several languages, convinced that a simple literal translation would capture a new audience. However, recent Eurostat studies show that a page detected as a "machine translation" registers an average of 45 % additional bounces.es compared with its native version. More than a semantic problem, it is the credibility of the brand that is affected. The 2023 edition of the Harvard Business Review report on digital trust shows a direct link between cultural perception and conversion rates. For a multilingual site, localisation must therefore evolve towards "SEO-optimised transcreation", a concept that combines cultural adaptation, search semantics and local keyword data.

Choosing an international URL architecture: ccTLD, subdomain or subfolder?

The debate between ccTLDs (e.g. : example.fr), sub-domain (ex : en.example.com) and sub-folders (e.g: example.com/en/) is a constant topic at SEO meetings. Each choice has a technical, marketing and legal impact. A Searchmetrics study (2022) of 18 million URLs confirms that ccTLDs have an initial advantage in terms of geographical relevance as perceived by Google, but suffer from a scattering of popularity signals. Conversely, a sub-domain pools domain authority, but can complicate the management of multi-lingual servers.

ccTLDs: local relevance, high costs

IKEA, which has a ccTLD strategy (ikea.fr, ikea.de), benefits from a hybrid image: each extension conveys an impression of national proximity. However, the company has had to deploy 30 parallel technical teams to manage the RGPD obligations specific to each territory. SMEs, lacking equivalent resources, will often prefer another model.

Sub-domains: flexibility and clean separation

Airbnb has long used a sub-domain for its Chinese blog (zh.airbnb.com) in order to comply with Great Firewall requirements. This decoupling made it easier to host the site in mainland China while keeping the main domain. The downside is that each sub-domain requires virtually independent netlinking in order to climb the regional SERPs.

Sub-folders: pooling popularity

Spotify, a follower of the example.com/es/benefits from the centralisation of its Domain Authority. The backlinks pointing to an English-language page indirectly benefit the Spanish, Italian or German versions. Nevertheless, the configuration of a CDN (Content Delivery Network) must be beyond reproach in order to maintain uniform loading times on a global scale.

Hreflang markup: matrix, pitfalls and best practice

Since 2011, the hreflang is the backbone of international SEO. Google, Bing and Yandex analyse it to direct users to the appropriate language or regional version. However, according to SEMrush, 37 % of the 10,000 most visited international sites have at least one hreflang loop error.

Building the complete matrix

Each URL must reference all its variants. Let's take example.com/en/, example.com/en/ and example.com/ca-en/. Each must contain three :

<link rel="alternate" hreflang="en" href="https://example.com/en/" />
<link rel="alternate" hreflang="fr" href="https://example.com/fr/" />
<link rel="alternate" hreflang="fr-ca" href="https://example.com/ca-fr/" />

Omitting a single link breaks the "chain of reciprocity" and can lead Google to consider the missing page as a duplicate or to ignore the directive.

Managing x-default

The attribute x-default directs users whose language is not explicitly covered. Amazon uses this to redirect users to a global country selection page. This strategy allows the giant to avoid a potentially intrusive automatic redirect, while at the same time clarifying its international offering.

Avoiding signal conflicts

The classic mistake: declaring hreflang="es-MX" tag and use a