Prompt Engineering

Prompt Cleaner

Clean and sanitize AI prompts instantly with this free prompt cleaner. Converts curly quotes, removes chat log prefixes (User:/Assistant:), strips invisible zero-width characters, auto-repairs unclosed code blocks, and optimizes token consumption for ChatGPT, Claude, and API payloads.

Total Fixes Applied
15cleanups
Quotes Straightened
8curly quotes
Chat Junk & Invisibles
6artifacts
Token Savings
5%~5 tokens saved
1-Click Cleaning PresetsSelect cleaning profile
Dirty Prompt Input
420 characters · ~105 tokensLive sanitization active
Sanitized Clean Prompt15 fixed
400 characters · ~100 tokensStructure in Prompt Formatter →
Cleaning Audit Report
Converted 8 curly quote(s) to standard ASCII
Removed 2 invisible Unicode character(s)
Stripped 2 chat log prefix(es)
Removed 2 web citation marker(s)
Auto-closed unclosed code fence

Example Walkthrough

Realistic transform preview

Input (Your prompt)

Human: [10:45 AM] You are a “Principal Content Strategist” — rewrite the executive briefing below…

Ensure the tone remains “authoritative yet approachable” and all key metrics are highlighted.

Guidelines:
• Keep the summary under 250 words total.
• Replace corporate jargon with clear, direct language.
• Retain all financial figures exactly as stated ($4.2M, 18% YoY growth) [1][2].​

```json
{
  “status”: “approved”

Output Result

You are a "Principal Content Strategist" - rewrite the executive briefing below...

Ensure the tone remains "authoritative yet approachable" and all key metrics are highlighted.

Guidelines:
• Keep the summary under 250 words total.
• Replace corporate jargon with clear, direct language.
• Retain all financial figures exactly as stated ($4.2M, 18% YoY growth) .

```json
{
 "status": "approved"
```

About this tool

Copying and sharing prompt text across software ecosystems—Google Docs, Notion, Word, Slack, and previous ChatGPT or Claude chat threads—injects disruptive hidden artifacts. Curly quotes (“”) corrupt JSON payloads and programming code snippets; chat history prefixes (such as “Human:”, “Assistant:”, “User:”) confuse LLM role definitions; web citation numbers ([1], [2]) introduce hallucination triggers; and zero-width spaces silently inflate token counts.

Our Prompt Cleaner is an intelligent sanitizer engineered specifically for modern AI workflows. Unlike generic text cleaners, it focuses on prompt-critical sanitation tasks: 1) Straightening typographic curly quotes into strict ASCII double and single quotes (`"` and `'`); 2) Stripping chat log headers and timestamps; 3) Repairing broken and unclosed markdown code fences (```); 4) Removing invisible Unicode characters and non-breaking spaces; and 5) Eliminating conversational filler phrases to minimize unnecessary token billing.

The interactive workbench offers 1-click presets tailored to distinct engineering needs: "Code & JSON Safe" (guaranteeing valid string quotes and intact code blocks), "AI Chat Log Clean" (converting previous conversation excerpts into clean prompt instructions), "Token Cost Optimizer" (aggressively pruning filler words and excess spacing), and "Typography Only" (polishing characters without modifying a single word).

All sanitation executes locally in your browser sandbox. Confidential system prompts, proprietary API payloads, and internal corporate instructions never leave your workstation.

How it works

  1. 1 1. Paste Dirty Prompt: Paste raw prompt text, copied chat logs, or document excerpts into the input box.
  2. 2 2. Select a Cleaning Preset: Choose 1-click profiles: Code & JSON Safe, AI Chat Log Clean, Token Cost Optimizer, or Typography Only.
  3. 3 3. Fine-Tune Granular Rules: Toggle smart quote conversion, chat prefix removal, code fence repair, citation stripping, or fluff elimination.
  4. 4 4. Inspect Live Audit Report: Review the real-time breakdown of converted quotes, stripped chat markers, and estimated token savings.
  5. 5 5. Copy or Chain: Copy the clean prompt, download it, or click "Structure in Prompt Formatter" to generate Claude XML or OpenAI Markdown.

Benefits

  • Code & JSON Reliability: Replaces smart quotes that cause runtime syntax errors in code and JSON parameters passed to LLMs.
  • Chat History De-duplication: Strips conversational prefixes ("User:", "Assistant:") and timestamps when repurposing chat logs into system prompts.
  • Token Cost Reduction: Eliminates redundant blank lines, trailing spaces, citation numbers, and conversational fluff phrases.
  • Auto-Repairs Code Fences: Automatically detects and closes orphaned markdown code blocks (```) to prevent formatting bleed.
  • Invisible Character Immunity: Cleans zero-width spaces, joiners, and non-breaking spaces that distort embedding models and tokenizers.
  • Transparent Audit Logging: Reports exact counts for every category of artifact cleaned with live percentage reduction metrics.
  • 100% Client-Side Privacy: No prompt text is transmitted or saved on external servers; everything runs locally in memory.

Use cases

  • Repurposing Chat Logs: Clean multi-turn ChatGPT or Claude transcripts to extract reusable system prompt templates.
  • Preparing JSON & Code Prompts: Ensure all prompt keys and strings use valid ASCII quotes before API submission.
  • Token Optimization for Production APIs: Strip polite conversational fluff and bloated whitespace across high-volume batch queries.
  • Document Paste Sanitization: Clean up prompts copied from PDF specifications, Word documents, or rich-text wikis.
  • Prompt Template Debugging: Fix invisible characters or curly quotes that cause variable interpolation or string match failures in LangChain/LlamaIndex.

Tips

  • Always clean prompts before passing JSON examples to LLMs; models often echo back invalid curly quotes if present in the prompt.
  • Use the "Token Cost Optimizer" preset for automated agents or RAG pipelines where per-call token efficiency directly impacts cloud bills.
  • After cleaning, send your text to the Prompt Formatter to add formal Claude XML tags or Markdown section headings.
  • If your prompt includes code snippets, verify that the "Code & JSON Safe" preset has closed all code fences.

Frequently asked questions

What is a prompt cleaner?

A prompt cleaner is an AI utility that sanitizes prompt templates before sending them to LLMs by replacing syntax-breaking smart quotes, stripping conversational fluff ("Hello ChatGPT"), removing chat log timestamps/roles, and repairing orphaned code fences.

What is the best prompt cleaner for AI models?

DevForge Prompt Cleaner is the best prompt cleaner because it offers targeted presets (Code & JSON Safe, Token Cost Optimizer, Chat History Cleaner), detailed before/after audit metrics, and direct chaining into the Prompt Formatter.

Why do smart quotes break AI prompts and code snippets?

Smart quotes (“ ” ‘ ’) are distinct Unicode characters from standard ASCII straight quotes (" and '). When code interpreters or JSON parsers inside LLMs encounter smart quotes, they throw syntax errors because the parser expects ASCII character codes 34 and 39.

What chat log artifacts does this tool remove?

It removes role prefixes (User:, Human:, Assistant:, AI:, System:, ChatGPT:, Claude:), timestamps ([10:45 AM], (12:00 UTC)), and citation markers ([1], [2], [citation needed]).

What conversational fluff phrases can be stripped?

Phrases like "Hello ChatGPT", "Please can you help me with", "I would like you to", "Thank you in advance", and conversational pleasantries that consume tokens without adding semantic guidance.

How does code fence auto-repair work?

The engine counts backtick fences (```). If an odd number of fences is detected (meaning a code block was opened but never closed), it automatically appends the closing fence to prevent markdown formatting issues.

Will cleaning change my instructions or prompt logic?

No. By default, the cleaner only normalizes typography, removes invisible Unicode, and cleans copy-paste artifacts. You have full granular control to enable or disable fluff stripping.

Is my prompt data private and secure?

Yes. All sanitization and token calculations occur 100% locally in your browser sandbox using client-side JavaScript. No prompt text or API keys are ever transmitted across the network.

Related tools

Prompt Formatter Structure AI prompts with Claude XML, OpenAI Markdown, Few-Shot blocks, and API JSON. Prompt Diff Compare two prompt versions with side-by-side visual diffs and token shift analytics. Invisible Character Detector Detect, highlight in-text, decode steganography, and sanitize 35+ hidden Unicode characters. Copy/Paste Cleaner Fix smart quotes, weird bullets and hidden junk from pasted text.

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