How to save and store electronic signatures in Flutter

Nutrient Flutter SDK can save electronic signatures so end users can reuse them across documents. This guide explains how to configure signature storage in your Flutter application.

Signature saving strategy

Use the SignatureSavingStrategy(opens in a new tab) enum to configure how Nutrient Flutter SDK handles signatures after creation:

NutrientDocumentView(
  documentPath: 'path/to/document.pdf',
  configuration: const NutrientViewConfiguration(
    signatureSavingStrategy: SignatureSavingStrategy.saveIfSelected,
    // Other configuration options...
  ),
)

Available strategies

Nutrient supports three signature saving strategies:

• SignatureSavingStrategy.neverSave — Nutrient never saves signatures for reuse. Use this strategy for one-time signatures or when you don’t want signature data to persist between sessions.
• SignatureSavingStrategy.alwaysSave — Nutrient saves signatures automatically for future use. Use this strategy when end users often reuse the same signatures.
• SignatureSavingStrategy.saveIfSelected — Nutrient saves signatures only when the end user chooses to save them. Use this strategy to give end users control over which signatures they keep.

Storage backends

When you set the saving strategy to alwaysSave or saveIfSelected, Nutrient configures signature storage automatically:

• iOS — Nutrient installs a keychain-backed PSPDFKeychainSignatureStore so saved signatures persist.
• Android — Nutrient configures a DatabaseSignatureStorage.

Web

On Web, your application manages stored signatures through the Web SDK signature storage API instead of a create-time strategy.

For Web-specific signature implementation details, refer to these guides:

• Nutrient Web SDK signatures
• Platform adapters — Use platform adapters to access the Web SDK instance directly.