Fern vs Liblab

The landscape of modern API SDK generation has evolved past community templates. Fern and Liblab represent the new-wave of API tooling: generators that prioritize developer experience, idiomatic code, and seamless CI/CD integration.

Major update: Both Fern and Liblab are now owned by Postman. Liblab was acquired in November 2025 and Fern was acquired on January 8, 2026. According to Postman, both products, brands, and roadmaps continue to operate independently — but this is a meaningful strategic context to factor into vendor selection decisions.

Fern Overview

Fern operates on an “Open Core” model. The SDK generator CLI is open-source (Apache 2.0), but advanced features (registry services, documentation hosting) belong to their commercial cloud tier. As of 2026, Fern supports 9+ languages including TypeScript, Python, Go, Java, C#, PHP, Ruby, Swift, and Rust.

Pros:

• Idiomatic Focus: Fern enforces strict typing and generates SDKs that feel incredibly native to the target language.
• Unified Docs + SDKs: Fern’s strongest differentiator is generating both SDKs and interactive API reference documentation from the same source — they are always in sync.
• Open CLI: The core generator runs entirely locally. Your spec never has to leave your environment.
• Protocol Breadth: Supports REST, WebSockets, and SSE natively. gRPC .proto files can be ingested for documentation, though gRPC SDK generation is currently limited to .NET/C#.
• Enterprise Features: 2025/2026 additions include RBAC, self-hosting options, and automated breaking-change detection.

Cons:

• Docs/Publishing Paywall: Seamless CI/CD publishing and documentation hosting are gated behind enterprise pricing.
• Opinionated: Fern can be strict about specification correctness; deeply malformed OpenAPI specs will fail compilation rather than generating degraded code.

Liblab Overview

Liblab, now part of Postman, is a commercial SDK-as-a-service provider. The Postman acquisition unlocks deep integration with the most popular API platform in the world.

Pros:

• Postman Integration: Instant SDK generation directly within the Postman platform is now available, enabling faster developer adoption.
• Zero-Touch CI/CD: Designed to integrate into GitHub Actions, GitLab CI, and Jenkins to fully automate SDK publishing to npm, PyPI, Maven, and more.
• MCP Generator: Liblab now generates MCP (Model Context Protocol) servers, turning your API into an AI-accessible interface for agents like Cursor.
• Modern Languages: Strong support for TypeScript (with Zod validation), Python, Go, Java, and Kotlin.

Cons:

• Postman Dependency Risk: Being acquired can shift product strategy. Teams should evaluate how deeply integrated the Liblab features are vs. standalone Postman.
• Portal as Add-on: The “unified developer portal” experience still relies on connecting ecosystem tools rather than being a fully owned, single-surface output.

Which Should You Choose?

Choose Fern if:

• You want a unified docs + SDK platform that outputs both from one spec, ensuring they never drift.
• You value the transparency of an open-source CLI where your spec stays local.
• You need protocol support beyond standard REST (WebSockets, SSE), or gRPC documentation generation from .proto files.

Choose Liblab if:

• You already use Postman and want zero-friction SDK generation baked into your existing workflow.
• Your team wants a fully automated, “no-touch” pipeline that pushes directly to all major package managers.
• AI agent integration (MCP servers) is a priority for your API strategy.