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By default, SLNG routes each request to the closest available region. Two HTTP headers let you override that: X-Region-Override pins a specific region, and X-World-Part-Override keeps traffic within a broader geographic zone.
X-Region-OverrideX-World-Part-Override
ScopeExact regionGeographic zone
Example valueeu-west-1eu
Use whenYou need a specific data centerYou want to stay in a geography without picking an exact region
If both are setWinsIgnored

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Regions

Not every model is deployed in every region. Check Models by Region to see what is available where.
World partRegion IDLocation
naus-east-1US East
naus-west-1US West
naus-central-1US Central
eueu-west-1EU West
eueu-west-2EU West 2
eueu-north-1EU North
apap-southeast-2AP Southeast
apap-south-1AP South
apap-southAP South (Sarvam)

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World parts

A world part groups several regions under one value. SLNG picks the best available region within that zone, but this does not guarantee your request will be served from a specific country.
ValueZone
naNorth America
euEurope
apAsia-Pacific
If you have data-residency or compliance requirements that depend on a specific country, use X-Region-Override with the exact region instead.

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Examples

curl https://api.slng.ai/v1/tts/slng/deepgram/aura:2 \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -H "X-Region-Override: eu-west-1" \
  -d '{ "text": "Hello from Europe!" }' \
  --output hello.wav
When both headers are present, X-Region-Override takes precedence and X-World-Part-Override is ignored. When neither is set, SLNG auto-selects the closest region.

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Need a model in a specific region?

Model availability varies by region. If you need a particular model hosted in a region or world part where it is not currently available, contact us and we can work with you on deployment options.

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Next steps

Models by region

See which models are deployed in each region.

HTTP vs. WebSocket

Pick the right protocol for your integration.