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Firma ships with complete localization in 7 languages, making it ready for teams across Europe and Latin America from day one.

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Supported languages

LanguageCode
Englishen
Spanishes
Italianit
Portuguesept
Frenchfr
Germande
Greekel
All UI elements — buttons, labels, notifications, emails, and error messages — are fully translated in each language.

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How language detection works

Firma uses a 2-tier fallback system to select the right language for each embeddable.

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1. Local storage

On return visits, Firma checks the browser’s local storage for a cached language preference. This provides instant language selection without a network request.

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2. Browser detection (default)

On a user’s first visit, Firma automatically matches the language to their browser or system language setting. If the detected language isn’t one of the 7 supported languages, Firma defaults to English.

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URL-based language override for embedded signing

You can force a specific language by appending the lang query parameter to any Firma URL: 
https://app.firma.dev/signing/{signing_request_user_id}?lang=es
This is useful when you want to:
  • Link directly into Firma in the correct locale for your users
  • Pre-select the language in embedded iframes
  • Test the signing experience in different languages

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Supported values

Use the two-letter language codes from the table above: en, es, it, pt, fr, de, el.

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Example: Embed signing in Spanish

<iframe
  src="https://app.firma.dev/signing/{signing_request_user_id}?lang=es"
  style="width:100%;height:900px;border:0;"
  allow="camera;microphone;clipboard-write"
  title="Firmar Documento"
></iframe>

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Localization in embeddable components

Firma’s embeddable components fully support localization:

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Non-persistent mode for iframes

When Firma is embedded in an iframe, language preferences operate in a non-persistent mode. This means the language is determined by:
  1. The lang URL parameter (if provided)
  2. The parent page’s context
This prevents embedded Firma components from overwriting language settings in the host application. Use the lang query parameter to control the language explicitly in iframe contexts.

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Example: Dynamic language selection

function embedSigning(signingRequestUserId, locale) {
  const iframe = document.createElement('iframe')
  iframe.src = `https://app.firma.dev/signing/${signingRequestUserId}?lang=${locale}`
  iframe.style.cssText = 'width:100%;height:900px;border:0;'
  iframe.allow = 'camera;microphone;clipboard-write'
  iframe.title = 'Sign Document'
  document.getElementById('signing-container').appendChild(iframe)
}

// Use the locale from your application
embedSigning('user_123', 'fr')

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Best practices

  • Use the lang parameter in embedded signing — Don’t rely on browser detection in iframe contexts. Pass the language explicitly to ensure a consistent experience.
  • Match your application’s locale — When embedding Firma, pass the same locale your application is using so the signing experience feels seamless.
  • Let users choose — For direct Firma links (e.g., in emails), omit the lang parameter and let Firma’s automatic detection handle it. Users who have set a preference will see their chosen language.