Best eSignature APIs for Linux

Foxit eSign is a secure, web-based, legally binding, HIPAA-compliant e-signature solution designed for organizations of all sizes. Easy to use and deploy, it enables businesses to create documents, send them for e-signatures, and securely archive them. Foxit eSign also offers robust API integrations and collaboration tools that allow teams across multiple locations to work seamlessly on the same contract or document. While many eSignature solutions focus only on signing, Foxit eSign integrates with Foxit Document Management System (DMS) to provide a connected workflow for signing, storing, organizing, and managing documents from start to finish.

Firma.dev is the developer-first e-signature API built for startups and mid-sized SaaS companies. With a clean REST API and embeddable template and signing editors, developers can ship e-signature workflows in hours, not weeks. Firma.dev's pricing model is straightforward: pay-as-you-go at just €0.049 (about 5 cents USD) per envelope. No monthly minimums, no contracts, no suprise fees. That's a fraction of the cost of legacy providers like DocuSign, which makes Firma.dev a strong fit for cost-sensitive teams scaling e-signature across products or customers. Every customer gets a dedicated workspace, a secure, partitioned space for templates, documents, and envelope usage. This makes it easy to manage usage by client or environment, with no cross-tenant exposure and no complex access rules. Firma.dev is designed with compliance in mind and aligns with key frameworks including the ESIGN Act, UETA, HIPAA, GDPR, and eIDAS. Security practices align with SOC 2 and ISO 27001 standard