Prompt Formatter — Format, Clean & Structure AI Prompts (Free, Private, Local)

Prompt Formatter — Clean, Structure & Inspect AI Prompts Instantly

Free, private, and lightning-fast. Paste a messy prompt and get a clean, consistently structured version you can copy into ChatGPT, Claude, Gemini, or any LLM API. All processing happens 100% in your browser — no servers, no API keys, no uploads.

How it works

1. Paste your prompt into the Input panel. Works with plain text, Markdown, XML-style prompts (<context>, <instructions>), JSON, YAML, and delimiter blocks (--- CONTEXT ---).
2. Format — one click normalizes whitespace, headings, bullets, numbered lists, code fences, and section headers without rewriting your meaning.
3. Copy — copy the formatted result or download as .txt / .md.

Deterministic and local. No LLM in the loop for the core formatting — the result is predictable and idempotent: formatting twice gives the same output.

Why format prompts?

• Whitespace waste: trailing spaces, 3–8 blank lines, mixed CRLF/LF add tokens and diff noise.
• Inconsistent structure: #role vs ## Role: vs ROLE: vs **Role:** makes prompts hard to scan and hard for LLMs to chunk.
• Delimiter chaos: <context> without a blank line, --- CONTEXT --- vs ### Context — models miss section boundaries.
• Bullet drift: •, *, -, – mixed, missing spaces.
• Code blocks: missing fences or inconsistent indentation breaks examples.
• Variables: typos like {{user_name}} vs {{username}} cause runtime failures.

A consistent prompt is easier to read, review, version-control, and cheaper to send via API.

What Format does (and doesn't do)

Does:

• Normalize line endings to LF, trim trailing whitespace per line
• Collapse 3+ blank lines to a single blank line
• Trim leading/trailing empty lines
• Preserve indentation inside ``` code blocks verbatim
• Normalize headings: #hello → # hello, trim extra spaces
• Normalize bullets: * / • → -, ensure single space after marker
• Normalize numbered lists: 1) → 1.
• Normalize section headers: Role:, --- CONTEXT ---, ### Task:, **Role:** → ## Role (allowlist of 20+ known sections)
• Normalize XML tags on their own line: < context > → <context>
• Idempotent — safe to run repeatedly

Never does (without explicit separate action):

• Rewrite instructions, change wording, invent requirements, alter code, alter examples, rename variables, change JSON/YAML semantics.

Clear separation: Format (deterministic clean) vs higher-level Improve/Optimize/Rewrite (which would need an LLM and is not part of this tool).

Operations

• Format — full pipeline: whitespace + markdown + sections + delimiters.
• Clean — whitespace only, no structural changes. Use when you want to keep original headings/bullets exactly.
• Minify — compact version: removes blank lines, collapses extra spaces. Useful for API payloads and token-sensitive workflows. Code blocks are preserved verbatim.
• Copy / Download / Clear — one-click.
• Diff view — side-by-side Original vs Formatted to see exactly what changed.

Prompt Inspector

Live, local-only stats:

• Characters, words, lines, estimated tokens (~4 chars/token — labeled as estimate)
• Sections found (Role, Context, Instructions, Constraints, Output Format, etc.)
• Variables/placeholders: {{name}}, {input}, ${variable}, [INPUT], <variable>
• Detected formats: Markdown, XML delimiters, Delimiters, Code blocks, JSON, YAML, Variables

Helps you spot missing sections or typos before you ship the prompt.

Supported input formats (detection, not conversion)

• Plain text / Markdown (headings, bullets, numbered lists, blockquotes, ``` fences)
• XML-style prompts (Anthropic style): <role>, <context>, <instructions>, <examples>
• Delimiter blocks: --- NAME ---, === NAME ===, ### NAME ###
• JSON / YAML prompt structures — detected, not rewritten
• Variables: mustache {{var}}, single-brace {var}, ${var}, bracket [INPUT], angle <var>

Shows a badge like: Format detected: Markdown + XML sections

Privacy

Prompts may contain API keys, credentials, proprietary logic, or personal data.

• Never sent to a server
• Never logged
• No analytics on prompt body
• No persistence unless you explicitly enable "Remember input" (stored locally in your browser, clearable)

Look for the "100% local" badge in the header.

Use cases

• ChatGPT / Claude / Gemini playground: clean pasted prompts before refining.
• Coding agents: normalize system prompts that contain repository context, constraints, and output schemas.
• RAG pipelines: ensure chunk boundaries align with ## Section headers.
• Teams: keep prompt files consistently formatted in git (idempotent formatting = no diff churn).
• API payloads: minify prompts to reduce tokens/cost.

Keyboard shortcuts

• Ctrl/Cmd + Enter — Format
• Ctrl/Cmd + Shift + C — Copy (formatted if present, else input)
• Ctrl/Cmd + L — Clear
• Ctrl/Cmd + K — Command palette (if platform supports it; otherwise Format is the primary action)

Format vs Clean vs Minify

Tips for great prompts

• Use explicit sections: ## Role, ## Context, ## Instructions, ## Constraints, ## Output Format.
• Prefer Markdown headings or XML tags — be consistent within one prompt.
• Put one blank line between sections, fenced code blocks with a language tag: ```js.
• Name variables consistently: pick one style ({{var}} recommended) and use a variables inventory to catch typos.
• Keep instructions numbered (1. 2.) for models to follow order.

FAQ

Is this free? Yes, free and static. No account, no API key.

Does it call an AI to format? No. Deterministic, local transformations only. Predictable and private.

Will it change my wording? No. It improves structure/whitespace/readability and never silently rewrites meaning.

How is token count estimated? Math.ceil(chars / 4) — a common English heuristic, labeled as "~ estimate". Real tokenization varies by model (GPT-4, Claude, Gemini). No heavy tokenizer is loaded to keep the tool fast.

Can I use it on mobile? Yes. Large editing areas, sticky toolbar, easy Copy button, responsive inspector and diff.

Can I download the result? Yes, as .txt or .md (same content, different extension).

Is formatting idempotent? Yes. Formatting an already-formatted prompt returns the same string.

Related tools

• AI Prompt Generator — build reusable prompt templates with typed variables
• Text Diff — compare prompt versions
• LLM JSON Cleaner — fix JSON returned by LLMs
• JSON Formatter / YAML Formatter — format structured data
• Regex Tester — validate variable placeholder patterns

Paste → Format → Copy. Fast. Local. Predictable.