Best Open Source Alternatives to Vellum

Compare the best free and open-source alternatives to Vellum — self-hosted and desktop replacements you fully control, ranked by GitHub stars, license and platform support.

Curated by open-source.store · Updated November 2026 · 3 alternatives

Vellum

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Vellum alternatives compared

Open-source alternatives to Vellum, compared by stars, license and platform
Tool		License	Platforms	Self-hosted
Langfuse	36,954	MIT	LinuxDockerWeb	Yes	Nov 2026	Visit
Phoenix	12,106	Apache-2.0	LinuxmacOSWindows	No	Nov 2026	Visit
Promptflow	11,260	MIT	LinuxmacOSWindows	No	Oct 2026	Visit

Top open-source Vellum alternatives

Langfuse36,954MIT

Langfuse is an open-source LLM observability platform and LangSmith alternative that delivers fast trace ingestion and self-hosted ClickHouse analytics.

LinuxDockerWeb

vs Vellum: a free, open-source option you fully control, licensed MIT.

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Phoenix12,106Apache-2.0

Phoenix is an open-source alternative to Arize AI and LangSmith providing self-hosted OpenTelemetry LLM tracing and evaluation without cloud data egress.

LinuxmacOSWindows

vs Vellum: a free, open-source option you fully control, licensed Apache-2.0.

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Promptflow11,260MIT

Promptflow is an open-source alternative to LangSmith for building, tracing, and evaluating LLM pipelines directly within private infrastructure.

LinuxmacOSWindows

vs Vellum: a free, open-source option you fully control, licensed MIT.

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Best Open Source Alternatives to Vellum

Vellum

Vellum alternatives compared

Top open-source Vellum alternatives

The modern standard for Protobuf workflows

Mentoring for backend developers. Consulting for startups.