v1.4.0 — Now with multi-model comparison

Mold your prompts.
Ship faster.
Break nothing.

The developer-first prompt engineering toolkit. Version, inject variables, live-test, and export to any LLM API — all in one terminal-native workspace.

4.2k GitHub Stars
12k+ Devs using it
98ms Avg. test latency

Everything a prompt engineer needs.

Built by devs who were tired of copy-pasting prompts into ChatGPT and calling it a workflow.

🗂️

Prompt Versioning

Track every iteration of your prompts with full diff history. Roll back to any version in one command. Git-style, but for prompts.

git-style diffs
💉

Variable Injection

Define {{variables}} in your prompts and inject dynamic values at runtime. Build reusable prompt templates that scale.

handlebars syntax

Live Preview & Testing

See rendered output in real-time as you type. Run A/B tests across prompt variants and compare responses side-by-side.

real-time eval
🚀

Export to Any LLM API

One-click export to OpenAI, Anthropic, Mistral, Cohere, and more. Auto-generates SDK-ready code snippets in Python, JS, or cURL.

10+ integrations

Three steps. Zero friction.

From blank canvas to production-ready prompt in under 60 seconds.

01

Write

Open the editor and write your prompt using our template syntax. Add variables, conditionals, and context blocks with full autocomplete.

# prompt.mold
You are a {{role}} assistant.
Task: {{task}}
Tone: professional
02

Test

Inject test values and fire live requests against your chosen model. Compare outputs, measure token cost, and iterate in real-time.

$ pm test --model gpt-4o
Injecting variables...
Running eval suite...
Score: 94/100
03

Deploy

Export your finalized prompt as a versioned API endpoint or copy SDK-ready code. Ship to production with confidence.

$ pm export --format openai
Prompt locked @ v2.3.1
Endpoint live
api.promptmolder.com/v1/...

Trusted by devs who ship.

★★★★★ 4,218 GitHub Stars
Open Source Core No vendor lock-in Self-hostable SOC 2 Ready

PromptMolder replaced my entire prompt-testing workflow. The variable injection alone saves me 2 hours a week. It's what Postman is to APIs, but for prompts.

AK
@alexkumar_dev Senior ML Engineer · Stripe

The versioning system is a game-changer for our team. We can finally track why a prompt change broke production and roll back instantly. Absolute must-have.

SR
@sara_r_codes AI Product Engineer · Vercel

I've tried 6 prompt tools. PromptMolder is the only one that feels like it was built by an engineer, not a PM. The CLI alone is worth it.

TN
@tnakamura_io Founding Engineer · YC W24

Start molding prompts
in 60 seconds.

Free forever for solo devs. No credit card. No BS. Just better prompts.

or: npm install -g promptmolder  ·  MIT Licensed