Serving users in many languages
Teams whose users search and read in different languages.
The problem
- Per-language indexes multiply infrastructure and keep each language's users inside their own corpus.
- Translating queries loses meaning at the boundary and doubles latency.
- Coverage is genuinely uneven across languages, and most stacks discover this only when a user complains.
The approach
- A single multilingual embedder places every supported language in one space, so a query in one language retrieves relevant passages in any other.
- The lang filter pins output language when the user needs one, and leaving it unset gives the best sources regardless.
- Facets on language show coverage distribution before you answer, so thin coverage is something you can state rather than something the user discovers.
The parameters that matter
| Parameter | Value | Why |
|---|---|---|
mode | semantic or hybrid | Keyword mode is monolingual by construction. |
lang | user’s language | Pin when the answer must be readable to them. |
facets | true | See language distribution before answering. |
tld[] | country codes | Approximate jurisdiction alongside language. |
# German query, sources in any language
curl -H "x-api-key: $UNLOB_API_KEY" "https://api.unlob.com/search?q=Klimapolitik&mode=semantic"
# Pinned to German sources
curl -H "x-api-key: $UNLOB_API_KEY" "https://api.unlob.com/search?q=Klimapolitik&lang=de"Where this is not the right tool
- Coverage is uneven across languages — English is by far the largest slice. Check the facets rather than assuming parity.
- Character-bigram tokenisation for CJK and Thai is robust but occasionally less precise than a language-specific segmenter.
Frequently asked questions
Do I need to translate queries?
No. Semantic and hybrid modes cross languages directly, and translating would search for the translation rather than the meaning.
How many languages are supported?
101 in the embedding space. The lang filter accepts the full ISO set, and the 30 highest-volume languages have their own pages with sample queries.
Build it on the free tier
10,000 requests a month, no card. Every parameter above works on every plan.