tapir
Tapir is a Scala library for building self-documenting HTTP APIs that automatically generate OpenAPI specifications. It provides type-safe endpoint definitions, integrates with major Scala HTTP frameworks (Akka HTTP, Play, http4s, ZIO), and supports both server and client implementations from a single declarative definition.
Key facts
Objective fields from the source. Values we can't verify are shown as “Unknown” rather than guessed.
| Field | Value |
|---|---|
| Repository | softwaremill/tapir |
| Owner | softwaremill |
| Primary language | Scala |
| License | Apache-2.0 — OSI-approved |
| Stars | 1.5k |
| Forks | 469 |
| Open issues | 159 |
| Latest release | v1.13.26 (2026-07-08) |
| Last updated | 2026-07-08 |
| Source | https://github.com/softwaremill/tapir |
What tapir is
Tapir uses declarative endpoint DSLs to separate API shape from implementation logic, enabling compile-time type safety and runtime OpenAPI/AsyncAPI/JSON Schema generation. It abstracts over multiple Scala server backends (Akka, Play, http4s, Netty) and supports rich integration with observability, JSON, and custom type libraries.
Get the tapir source
Clone the repository and explore it locally.
git clone https://github.com/softwaremill/tapir.gitcd tapir# follow the project's README for install & configurationNeed it deployed, integrated, or customized instead? DEV.co ships production installs.
Best use cases
Implementation considerations
- Choose a compatible server backend (Akka, Play, http4s, ZIO, or Netty); verify dependency alignment with existing project stack to avoid version conflicts.
- Define endpoints early; the declarative model encourages API design-first but requires initial upfront schema definition before implementation.
- Leverage sttp client integration for consistent request/response codecs between server and client endpoints to minimize serialization bugs.
- Plan observability instrumentation; Tapir's metadata enables rich tracing, but integration requires explicit setup (e.g., with Prometheus, Jaeger, or OpenTelemetry).
- Test endpoint definitions separately from handler logic; the separation enables unit testing of routing and schema validation independently.
When to avoid it — and what to weigh
- Non-Scala ecosystems — Tapir is Scala-specific. Java, Python, Go, or Node.js teams cannot use it directly without significant interop overhead.
- Simple REST APIs with minimal type safety requirements — The declarative overhead and type-system complexity may be unnecessary for trivial endpoints; lightweight frameworks may be faster to prototype.
- Teams unfamiliar with functional programming idioms — Tapir assumes comfort with Scala's type system, functional composition, and integration patterns. Steep learning curve for imperative-only backgrounds.
- Projects requiring cutting-edge HTTP/3 or exotic protocol support — Tapir is HTTP/1.1 and HTTP/2 focused. Niche protocol requirements may not be covered by existing server integrations.
License & commercial use
Apache License 2.0 (Apache-2.0) is a permissive, OSI-approved license allowing commercial use, modification, and distribution with attribution and patent protection. No explicit restrictions on closed-source derivatives.
Apache 2.0 permits commercial use without requiring code release or license propagation. Organizations can use Tapir in proprietary products. However, confirm compliance with your legal team regarding patent indemnity clauses and attribution requirements in derived works.
DEV.co evaluation signals
Editorial assessment — not user reviews. Directional, with an explicit confidence level.
| Signal | Assessment |
|---|---|
| Maintenance | Active |
| Documentation | Strong |
| License clarity | Clear |
| Deployment complexity | Low |
| DEV.co fit | Good |
| Assessment confidence | High |
Tapir itself does not implement authentication or authorization; those are delegated to handler logic or middleware. HTTPS/TLS is configured at the server backend level, not in Tapir. Input validation and output encoding rely on codec libraries and handler code—no automatic protection against injection or XSS. Review server backend security advisories (Akka, Play, http4s, Netty) and ensure timely patching. No explicit security audit or penetration test data in public domain.
Alternatives to consider
OpenAPI/Swagger frameworks (e.g., tapir for Python/Go alternatives like FastAPI, Gin, Echo)
Language-agnostic alternatives exist for non-Scala teams; however, they lack Tapir's compile-time type safety and functional composition model.
Play Framework + OpenAPI plugins
If already using Play, a lighter-weight OpenAPI generator may reduce dependencies; but loses Tapir's server abstraction and declarative endpoint composability.
http4s with manual OpenAPI generation
More minimal but requires hand-writing OpenAPI specs or relying on external code generation tools; trading off developer ergonomics for reduced overhead.
Build on tapir with DEV.co software developers
Tapir accelerates Scala API projects with compile-time guarantees and automatic documentation. Explore tutorials, review integrations, and assess fit with your team's functional programming maturity and backend framework choice.
Talk to DEV.coRelated open-source tools
Surfaced by semantic similarity across the DEV.co open-source index.
Related on DEV.co
Explore the category and the services that help you build with it.
tapir FAQ
Can I use Tapir with existing Akka HTTP / Play routes?
Does Tapir enforce a specific JSON library?
Is OpenAPI generation automatic?
What is the performance overhead compared to native server frameworks?
Software development & web development with DEV.co
From first prototype to production, DEV.co delivers software development services around tools like tapir. Our software development agency staffs experienced software developers and web developers for custom software development, web development, integrations, and ongoing support across open-source observability and beyond.
Ready to streamline API development with type-safe declarations?
Tapir accelerates Scala API projects with compile-time guarantees and automatic documentation. Explore tutorials, review integrations, and assess fit with your team's functional programming maturity and backend framework choice.