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The workbench for the prompt layer

Stop guessing which prompt works.

Break any prompt into bloks, see exactly what each one adds to the prompt you ship, and keep every version. When something breaks, find the blok that did it.

Start free See how it works
Prompts and versions
∞ on Free
Card to sign up
None
Models
Bring your own
Sheet 01 · Decompilesupport-reply.promptPasted · 4 sentences
ContextB1You are a support agent for Northwind Outfitters.
ConstraintB2Reply in under 80 words. Greet the customer as {{name}}.
ExampleConflicts with B4“I’ve issued a full refund, sorry for the trouble.”
ExpectsConflicts with B3Never promises a refund.
41promptsSheet 01Scale 1:1Rev 7

How it works

From a wall of text to parts you can name.

  1. Bring the prompt you already run. Markdown and variables like {{name}} stay exactly as you wrote them.

    Free

  2. Context, constraint, example, expects. Each blok owns a span of the final prompt, so you always know which part says what. Drag to reorder.

    Free

  3. Copy the compiled prompt in one click. Expects bloks never reach the prompt. With Performance they become tests you run on every model.

    Copy is freeTests · Performance
Sheet 02 · Pasted · 8 linesSheet 02State 1/3

Free plan · Unlimited

Everything you need to write, keep and ship a prompt. Free, with no limits.

No trial clock, no prompt cap, no version cap. The Free plan is the whole workbench for writing prompts.

Bill of materialsPlan · Free
ItemPartQtyNotes
M01Account1Email link, Google or GitHub. No card.
M02PromptsPaste one in or start blank.
M03Bloks per promptContext, constraint, example, expects.
M04Compiled prompt, one-click copyAs a template, or with variables filled.
M05VersionsEvery save is a version. Restore in one click.
M06Run on one modelWith your own key. The provider bills you directly.
M07Your models20+ providers, any OpenAI-compatible endpoint, or a model on your machine.
M08Library with search by name1Private by default.
M09Export everythingMarkdown and JSON in one .zip.
M10Delete account1Removes every prompt, version and saved model.
41promptsSheet 03Free planStart free

Performance plan

Know which blok broke it.

Performance adds the tools that test, measure and share a prompt. Every one of them works on the bloks you already have, so nothing changes about how you write.

P01 Performance

A red cell that points at a line.

Every check comes from a blok. When a check fails, 41prompts traces the failure back to the blok most likely to have caused it, with a confidence score, on each model separately.

  • Failures attributed per model, not per prompt
  • Click a failure to jump to the blok
  • Checks that could not be graded are reported as that, never as a pass

Example · one suite, three models

Check, and the blok it came fromGPTClaudeGemini
B2 Reply under 80 words40/4040/4039/40
B1 Stays in role40/4040/4040/40
B4 Never promises a refund40/4038/4031/40
ExampleB3Likely cause · 82% · Gemini

“I’ve issued a full refund, sorry for the trouble.”

P02 Performance

Find what nothing checks.

The linter reads your prompt on import and flags repeated rules, contradictions and lines no test could ever verify.

You are a support agent for Northwind Outfitters. Keep replies short. Reply in under 80 words. Always offer a full refund when an order is late. Never promise a refund. Be helpful and friendly.

  1. 1Repeats “Reply in under 80 words.”
  2. 2Conflicts with “Never promise a refund.”
  3. 3Untestable. Nothing can check “helpful”.

P05 Performance

One prompt, every model.

Run the same suite on any of your models side by side, hosted or local, with what each run cost and how long it took.

Example · 200 checks per model

ModelPassedCostp50
Claude191/20037¢1.4s
GPT188/20041¢1.2s
Gemini178/20012¢0.9s

  • P03

    Decompiler

    Paste a long prompt and get it back as typed bloks, with nothing lost.

  • P04

    Tests from expects

    Each expects blok becomes a check. No test code to write.

  • P06

    Search and tags

    ⌘K across names, tags and the text inside every blok.

  • P07

    Semantic diff

    See changes per blok, next to the test results they changed.

  • P08

    Shared workspaces

    Invite by link. Owner, editor and viewer roles. One shared library.

  • D01

    Share pages

    A public, read-only page of a prompt’s bloks and findings. Free to view.

  • D02

    Typed export

    Download any prompt as a typed .ts or .py function.

  • D03

    Presence

    See who else has a prompt open before you save over them.

Questions

Before you paste anything.

Is my prompt private?

Yes. Every prompt and version is visible only to you. Nothing becomes public unless you create a share page, which needs Performance, and you can take that page down at any time.

What do you do with my API keys?

They run your prompts on the provider you choose and nothing else. Keys are encrypted at rest, shown once when you save them, and never written to logs. The provider bills your own account. A model on your own computer or network runs straight from your browser, so its requests and its key never touch our servers.

Which models can I use?

Any model from 20+ hosted providers, such as OpenAI, Anthropic, Google, OpenRouter, Azure, Bedrock, Mistral and Groq; any OpenAI-compatible endpoint; or a model on your own machine through Ollama or LM Studio. Add as many as you like, each with its own label. Local models run from your browser: Chrome and Edge reach them anywhere on your network after asking once, Firefox reaches models on the same computer, and Safari needs the model served over https.

What is free, exactly?

Everything you need to write, save, version, run once and copy a prompt, with no limits on prompts, bloks or versions. Testing, analysis, comparison and sharing are in Performance.

What is a blok?

One typed part of a prompt: context, constraint, example or expects. Each blok owns an exact span of the compiled prompt. Expects bloks describe what a good answer does, and never appear in the prompt itself.

Paste a prompt.
See what is in it.

Start free See how it works

Free, unlimited, no card.

Using 41prompts? A short review on Product Hunt helps other people find it.

41Prompts - Stop guessing which prompt works | Product Hunt