Prompt Template Filler
Write a prompt with {{variable}} placeholders, fill the auto-detected inputs, and copy the substituted result. Free, reusable, runs in your browser.
Prompt Template Filler
How to Use the Prompt Template Filler
Write your template
Type a prompt you reuse often, and replace the parts that change with double-curly placeholders like {{product}} or {{audience}}. Names can use letters, numbers, underscores, dots and hyphens.
Fill the detected variables
Every unique placeholder is detected automatically and gets its own labelled input below the template. Type a value into each — the list updates instantly whenever you edit the template.
Watch it substitute live
As you type, the filled prompt updates in real time. Any placeholder you leave blank stays visible as {{variable}}, and the status line shows how many variables are filled.
Copy and reuse
Hit Copy and paste the result into ChatGPT, Claude, or any tool. Tweak a value and copy again to run the same template with new inputs. Everything happens in your browser — nothing is uploaded.
Stop Rewriting the Same Prompt — Turn It Into a Template
Why prompt templates beat copy-paste-and-edit
If you use the same kind of prompt over and over — a product description, a cold email, a bug report, a lesson plan — you have probably been copying an old message and hand-editing the bits that change. That works until it doesn't: you miss a spot, you leave last week's client name in, or you forget the length limit you always add. A prompt template fixes that by separating the fixed structure of your prompt from the few values that actually vary between uses. You write the structure once, mark the variable parts with {{placeholders}}, and from then on you only fill in the blanks.
This tool uses the most widely recognised placeholder syntax — double curly braces, as in {{topic}} or {{word_limit}}. The moment you type one into the template, it is detected and a matching input appears. The same pattern shows up everywhere in software, from email merge fields to templating languages like Handlebars and Mustache, so the habit you build here transfers directly to spreadsheets, mail-merge, documentation generators, and most low-code automation platforms. A variable name can hold letters, numbers, underscores, dots and hyphens, which is enough to keep names readable — {{customer.first_name}} reads better than {{x1}}, and a clear name is itself a small piece of documentation for whoever fills the template next.
"A good template is a prompt you only have to think hard about once. After that, it is just blanks to fill — and blanks are far harder to get wrong than free-form text."
Reuse, consistency, and fewer mistakes
The real payoff of templating is consistency. When a prompt always asks for the same structure — the same tone, the same length, the same closing instruction — the output you get back is consistent too, which matters whether you are one person keeping your own work uniform or a team trying to sound like one voice. A template is also the easiest thing in the world to share: hand someone the template text and the variable names, and they can produce the same quality of prompt you do without understanding every nuance of why it is worded the way it is. That is how prompt libraries are built. Teams collect their best-performing templates, give each variable a clear name, and let everyone fill them in rather than reinventing the prompt each time.
Because this filler keeps unfilled placeholders visible as {{variable}} rather than silently deleting them, it doubles as a checklist: a glance at the output tells you exactly what you still have to supply, and the status line counts it for you. Preserving the values you have already typed when you edit the template means you can refine the wording without losing your work. And since the whole thing runs as plain JavaScript in your browser — no account, no server round-trip, no storage — you can paste sensitive or pre-release text in safely, fill it, copy it, and close the tab knowing nothing left the page. Build the template once, reuse it forever, and let the structure do the remembering for you.
10 Facts About Prompt Templates
A prompt template separates the fixed structure of a prompt from the few values that change each time you use it.
Double curly braces — {{like_this}} — are the most widely recognised placeholder syntax across software.
The same {{ }} pattern powers templating engines like Handlebars and Mustache, and most mail-merge fields.
This tool auto-detects every unique placeholder and builds an input for each one as you type.
A clear variable name like {{customer.first_name}} is a tiny piece of built-in documentation.
Templates give you consistency — same structure in, same shape of answer out, every time.
Sharing a template plus its variable names lets a teammate reproduce your prompt without reverse-engineering it.
Unfilled placeholders stay visible here as {{variable}}, so the output doubles as a checklist.
The best prompt libraries are just collections of templates with well-named blanks to fill.
This filler runs entirely in your browser — your template and values are never uploaded.
Frequently Asked Questions
- A prompt template is a reusable prompt where the parts that change are written as placeholders instead of fixed text. You write the structure once, mark the variable parts with {{double curly braces}}, and then just fill in the blanks each time you use it.
- Double curly braces: {{variable}}. A name can contain letters, numbers, underscores, dots and hyphens — for example {{product}}, {{word_limit}} or {{customer.first_name}}. Spaces inside the braces are allowed and ignored.
- Automatically. Every unique placeholder in your template gets its own labelled input below the template box. As you edit the template, the input list re-detects in real time — new placeholders add inputs and removed ones drop away.
- They stay visible in the output exactly as {{variable}}, so you can see at a glance what is still missing. The status line also counts how many variables are filled out of the total.
- No. Values are preserved for any variable that still exists after the edit, so you can reword the template freely. Only variables you remove entirely have their values cleared.
- Yes. Repeated placeholders with the same name share a single input, and every occurrence is replaced with that value. This is handy when a name or product appears several times in one prompt.
- Anywhere that takes plain text — ChatGPT, Claude, Gemini, an agent's prompt field, an email, or a document. The output is ordinary text with the placeholders substituted, so it is not tied to any particular tool.
- No. The substitution runs entirely in your browser with plain JavaScript. Nothing you type — the template or the values — is sent to any model, server, or third party, and nothing is saved when you close the tab.
- It uses the same {{ }} placeholder style, which is why it feels familiar. This tool does straight variable substitution only — it does not run loops, conditionals or helpers like full templating engines do, which keeps it simple and predictable.
- The tool itself does not store anything, but the template is just text — copy the template box into a note, a doc, or your team's prompt library to keep it. Anyone you share it with can paste it back in and fill the same variables.
- Completely free, with no account or sign-up and no limit on use. It runs in your browser and collects no data.
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