Large Language Models have changed how we think about application logic. Prompts are no longer "just text" - they are configuration, business rules, and behavioral contracts for the model. As soon as a team starts iterating on prompts, they begin to multiply: new variants, experiments, context adjustments, formatting tweaks, role changes, and domain‑specific constraints.

Very quickly, teams face the same problems they once had with configuration files and microservice contracts:
Where do we store prompts? How do we version them? How do we share them across services? How do we secure them?

For engineering teams, the answer is clear:
a dedicated prompt registry with REST API, RBAC, tagging, versioning, and On‑Premise deployment options. It would also be great if the product were free of charge.

Below is a brief overview of existing solutions.

Existing Solutions:

PromptHub
Cloud prompt manager with UI, versioning, A/B testing, and integrations.
REST API: Yes · RBAC: Partial · On‑Premise: No · Scaling: SaaS · License: Freemium

PromptPal
Hybrid cloud/on‑prem prompt manager.
REST API: Yes · RBAC: Yes · On‑Premise: Yes · Scaling: Docker/K8s · License: Unknown

Notion
General knowledge tool sometimes used for prompts.
REST API: Yes · RBAC: Limited · On‑Premise: No

PromptMan
PromptMan is the only tool in this list designed from the ground up as a REST API‑first prompt registry.
It is not a UI‑driven SaaS product — it is an engineering‑grade service intended to be embedded into real backend architectures.

PromptMan provides:

• Full CRUD for prompts
• Versioning, tagging, collections
• Authentication and authorization
• RBAC
• Read‑only roles
• Multiple database backends
• Performance benchmarks for different DB engines
• Stateless architecture
• Horizontal scaling
• 100% On‑Premise

Also as Docker images:

• Docker Hub
• Github

This makes PromptMan the closest analogue to a "PostgreSQL for prompts": a reliable, API‑driven, infrastructure‑level component.

Comparison Table

Tool    REST API    RBAC    On‑Premise    Scaling Price
PromptHub   ✔ Partial ✖ SaaS    Freemium
PromptLayer ✔ ✖ ✖ SaaS    Freemium
LangSmith   ✔ Partial ✖ SaaS    Freemium
Promptfoo   ✔ ✖ ✔ CI/CD   Free
Flowise ✔ ✖ ✔ Docker  Free
PromptPerfect   ✔ ✖ ✖ SaaS    Paid
PromptPal   ✔ ✔ ✔ Docker  ?
Notion  ✔ ✖ ✖ SaaS    Freemium
Obsidian    ✖ ✖ ✔ Git Free
Dendron ✖ ✖ ✔ Git Free
PromptMan   ✔ ✔ ✔ Horizontal  Free

Why PromptMan Is the Best Choice for On‑Premise Teams:

• Security — prompts never leave your infrastructure.
• REST API‑first — easy integration with any backend or microservice.
• RBAC — strict control over who can read, write, or manage prompts.
• Scalability — stateless service, horizontally scalable.
• Database flexibility — SQLite for dev, PostgreSQL/MySQL for prod.
• Automation‑friendly — ideal for CI/CD, prompt pipelines, and multi‑service architectures.
• Open‑source — no vendor lock‑in, no SaaS dependency.

For teams that need a local, secure, scalable prompt registry with real API semantics, PromptMan stands out as the most engineering‑friendly solution available today.