--- title: "Android PDF signature library: Fast and easy setup | Nutrient" canonical_url: "https://www.nutrient.io/guides/android/signatures/" md_url: "https://www.nutrient.io/guides/android/signatures.md" last_updated: "2026-05-23T00:08:17.999Z" description: "Unlock the secrets of enhancing digital signatures on Android with expert tips and guidance. Learn more at Nutrient." --- # Android PDF signature library Nutrient Android SDK is a library for signing PDF documents with an electronic signature or with encrypted certificate-based digital signatures. It offers developers an API to create, validate, and display digitally signed documents, as well as a beautiful UI for hand-drawn electronic signatures. ## Introduction to signatures Nutrient facilitates paperless signing workflows with the [Electronic Signatures](https://www.nutrient.io/sdk/solutions/signing/) and [Digital Signatures](https://www.nutrient.io/sdk/solutions/signing/) components. These are two components that can be licensed separately and don’t depend on each other. [Learn more](https://www.nutrient.io/guides/android/signatures/overview.md) ## Electronic signatures --- **Add an ink electronic signature** How to add an electronic signature (eSignature) to a PDF document [Read more](https://www.nutrient.io/guides/android/signatures/adding-an-electronic-signature.md) --- **Electronic signature storage** How to implement a mechanism for storing signatures [Read more](https://www.nutrient.io/guides/android/signatures/signature-storage.md) --- **Electronically sign with a certificate** How to use electronic signatures and digital signatures together [Read more](https://www.nutrient.io/guides/android/signatures/using-electronic-signatures-and-digital-signatures-together.md) ## Digital signatures --- **Supported digital signature methods** Learn about supported digital signing methods and algorithms [Read more](https://www.nutrient.io/guides/android/signatures/digital-signatures/supported-methods.md) --- **Generate a certificate** How to generate a self-signed certificate for testing purposes [Read more](https://www.nutrient.io/guides/android/signatures/digital-signatures/signature-lifecycle/prepare-the-certificates-for-signing.md) --- **Add a digital signature** How to add a digital signature to a PDF document [Read more](https://www.nutrient.io/guides/android/features/digital-signatures.md) --- **Validate digital signatures** How to validate digital signatures [Read more](https://www.nutrient.io/guides/android/signatures/digital-signatures/signature-lifecycle/validation.md) --- **Biometric digital signatures** How to create a digital signing solution based on biometric data [Read more](https://www.nutrient.io/guides/android/signatures/digital-signatures/signature-lifecycle/biometric.md) ## Combine with forms --- **Add a signature field** How to programmatically add new signature form fields to a PDF [Read more](https://www.nutrient.io/guides/android/signatures/digital-signatures/signature-lifecycle/add-a-signature-field.md) --- **Fill and sign forms** How to programmatically or manually fill and sign forms in a PDF [Read more](https://www.nutrient.io/guides/android/signatures/fill-and-sign-forms.md) **Call to Action** Start your free trial for unlimited access and expert support. [Learn More](https://www.nutrient.io/sdk/android/getting-started.md) --- ## Related pages - [Easily fill and sign PDF forms on Android](/guides/android/signatures/fill-and-sign-forms.md) - [Understanding electronic and digital signatures](/guides/android/signatures/overview.md) ## Pages in this section - [Robust digital signature support on Android](/guides/android/signatures/digital-signatures/supported-methods.md) - [Understanding digital signatures in Android apps](/guides/android/signatures/digital-signatures/overview.md) - [Understanding PAdES and CAdES digital signatures](/guides/android/signatures/digital-signatures/standards.md) - [Troubleshoot digital signatures on Android devices](/guides/android/signatures/digital-signatures/troubleshooting.md) - [How to add electronic signatures to PDFs on Android](/guides/android/signatures/adding-an-electronic-signature.md) - [eSign PDFs with a certificate on Android](/guides/android/signatures/using-electronic-signatures-and-digital-signatures-together.md) - [How to save and store electronic signatures on Android](/guides/android/signatures/signature-storage.md) - [How to maintain valid digital signatures on Android](/guides/android/signatures/troubleshooting/multi-signatures-previous-not-valid.md) - [Understanding digital signature validation states](/guides/android/signatures/troubleshooting/chain-of-certs-not-valid.md) - [How to add signature fields to PDFs on Android](/guides/android/signatures/digital-signatures/signature-lifecycle/add-a-signature-field.md) - [Biometric signatures on Android](/guides/android/signatures/digital-signatures/signature-lifecycle/biometric.md) - [Master digital signatures in Android efficiently](/guides/android/signatures/digital-signatures/signature-lifecycle/overview.md) - [External signing services on Android](/guides/android/signatures/digital-signatures/signature-lifecycle/external-signing-service.md) - [How to create and validate digital signatures on Android](/guides/android/signatures/digital-signatures/signature-lifecycle/prepare-the-certificates-for-signing.md) - [Sign a PDF with a certificate on Android](/guides/android/features/digital-signatures.md) - [Configure digital signature appearance in Android: Visible vs. non-visible signatures](/guides/android/signatures/digital-signatures/signature-lifecycle/signature-appearance.md) - [Securely validate digital signatures in Android apps](/guides/android/signatures/digital-signatures/signature-lifecycle/validation.md)