PromptDC vs Merlin
Updated July 2026
PromptDC's flagship desktop app works everywhere on macOS and Windows: select text in any app, every browser, IDE, or terminal, press Cmd+Shift+E or Ctrl+Shift+E, review the editable result, then Replace or Copy. Add the Chrome extension for in-place web rewriting without Accessibility permission or an IDE extension for its focused editor workflow. Merlin is typically used for an all-in-one ChatGPT browser sidebar.
PromptDC's macOS and Windows desktop app rewrites selected text in any app, every browser, IDE, and terminal, with a default profile for each application.
PromptDC's writing profiles handle grammar, email, replies, tone, posts, summaries, explanations, and concise rewrites.
Merlin is typically stronger for an all-in-one ChatGPT browser sidebar.
The optional Chrome extension adds in-place rewriting, per-website default profiles, and no Accessibility permission.
Optional IDE extensions add a target-agent picker and Simple or Structured output; the desktop app already covers IDE chat panels and terminals.
The core difference
PromptDC is a profile-driven desktop writing and prompt app for macOS and Windows that works everywhere: any desktop app, every browser, IDE, and terminal. Select text, press Cmd+Shift+E or Ctrl+Shift+E, review the editable result, then Replace or Copy. Grammar, Email, Social, Summarize, Professional, Image Prompt, Reply, Concise, Explain, and Code profiles cover everyday writing and AI prompts.
Unlike writing assistants confined to supported sites, the PromptDC desktop app rewrites selected text in any app, every browser, IDE, and terminal on macOS and Windows. The optional Chrome extension adds in-place web rewriting and per-website profiles, while optional IDE extensions add focused editor AI chat workflows.
The macOS and Windows desktop app can assign a default profile to each application and already covers every browser, IDE chat panel, and terminal. The optional Chrome extension adds per-website defaults and in-place editable-field rewriting without Accessibility permission. Optional IDE extensions add a target-agent picker and Simple or Structured output.
What Merlin is best for
Merlin is an all-in-one AI browser assistant that adds a ChatGPT-style sidebar for asking questions, summarizing pages, and writing across the web.
Merlin is a broad AI sidebar; PromptDC rewrites selected text across desktop apps, the terminal, Chrome, and supported editors.
Side-by-side comparison
| Category | PromptDC | Merlin |
|---|---|---|
| Primary use case | Improve selected writing and AI prompts anywhere on macOS and Windows. | an all-in-one ChatGPT browser sidebar |
| Where it works | Desktop app: any app, every browser, IDE, and terminal on macOS and Windows. Chrome and IDE extensions are optional additions. | Sidebar across the web; chat-driven workflow. |
| What it rewrites | Grammar, email, social, summaries, tone, prompts, and more. | Chat answers, summaries, and writing via the sidebar. |
| Profiles & Actions | 10 built-in profiles plus custom profiles and Actions. Desktop supports per-app defaults; Chrome supports per-website defaults. | Chat presets, not per-site rewrite profiles. |
| Code prompts | The Code profile creates implementation-ready prompts for AI coding tools and terminal CLIs. | Chat-based; not in-place prompt rewriting. |
| Current pricing | No free tier. Pro is $9/month. Lifetime starts at $69 one time with BYOK. | Free plan available. Merlin Pro is $19/month on the official pricing page, with shared fair-use limits across models and features. |
Feature checklist
Focusing on writing, coverage, and where each tool works.
| Capability | PromptDC | Merlin |
|---|---|---|
| Works in any app, every browser, IDE, and terminal on macOS and Windows | Yes | Partial (sidebar) |
| Grammar and tone correction | Yes | Partial |
| Writing profiles for email, social posts, and summaries | Yes | Yes (via chat) |
| Per-website default profiles | Yes | No |
| Improves AI prompts (ChatGPT, Claude, Gemini) | Yes | Partial |
Before & after
Your text
make this message more polite: no we cant extend the deadline
PromptDC enhanced
Unfortunately we're not able to extend the deadline this time, but I'm happy to help prioritize what's most important before then.
Why choose PromptDC over Merlin?
You want one macOS or Windows desktop install for every app, browser, IDE chat panel, and terminal.
You need Grammar, Email, Social, Summarize, Professional, Image Prompt, Reply, Concise, Explain, and Code profiles.
You want custom profiles, Actions, and per-app default profiles.
You want optional Chrome and IDE extensions for per-website defaults and focused editor workflows.
Choose Merlin if
You want one sidebar with access to multiple premium text, image, and video models without managing provider API keys.
You need page chat, deep research, projects, spreadsheet analysis, YouTube summaries, or a large catalog of AI tools.
You want a free plan for limited model and extension access.
A broad AI workspace is more important than focused in-place rewriting and a lifetime BYOK option.
A broad AI workspace versus a focused rewrite layer
Merlin is designed as an all-in-one AI browser workspace. Its official pricing page highlights multiple frontier models, projects, spreadsheet analysis, deep research, page chat, image and video generation, and a catalog of more than 70 AI tools. The Chrome extension opens a chat-oriented workflow beside the current page.
PromptDC has a narrower interface. On desktop, select text in any app, choose a writing profile or the Code profile, review the result, then decide whether to paste it. In Chrome, editable content is rewritten in place while a result from a read-only page is copied. Supported editor extensions rewrite prompts in the editor's AI chat panel. This reduces context switching when the task is improving existing text, but it does not attempt to replace Merlin's research, model chat, media generation, and project features.
The honest decision is based on breadth. Merlin can consolidate several AI activities into one subscription. PromptDC can make one repeated activity faster across desktop apps, Chrome, and supported editors: turning rough text into a clearer message, summary, post, reply, or prompt.
Pricing and usage limits
Merlin's official page lists a free plan and Pro at $19 per month. Pro includes expanded model and extension usage, but Merlin states that features share a combined fair-use limit. Heavy use of one feature can reduce availability elsewhere, and additional credits may be sold when limits are reached.
PromptDC has no free tier. Pro costs $9 per month. Lifetime starts at $69 one time with BYOK support. Merlin bundles model access into its service, while PromptDC Lifetime uses your own key.
Merlin's higher subscription can be justified when it replaces separate chat, research, image, video, and document tools. PromptDC is less expensive when the core need is rewriting and prompt improvement rather than a full multi-model workspace.
Which workflow creates less friction
Choose Merlin when you regularly ask questions about the current page, compare models, maintain projects, analyze files, or generate media. Its sidebar is useful because the assistant remains available even when no text is selected. Choose PromptDC when you already know what text needs improvement and want the output returned directly to the original workflow.
For either tool, do not assume model access means unlimited use. Review fair-use rules, model-specific caps, file limits, and renewal terms. For business text, confirm privacy requirements before sending sensitive content and check every generated result for factual accuracy.
- Merlin is stronger for multi-model chat, research, projects, files, and media creation.
- PromptDC is stronger for direct profile-based rewriting and a pay-once BYOK route.
- The two products overlap on writing and summaries but differ substantially in scope.
Recommended when
- Rewriting selected text in native desktop apps and improving prompts in the terminal
- An AI writing assistant that works on any website
- A Grammarly alternative for AI prompts and chat
- Fixing grammar, tone, or clarity in any selected text
- Rewriting emails, replies, and social posts with AI
- Improving prompts before sending them to ChatGPT, Claude, or Gemini
- Per-website writing profiles for everyday AI tasks
Common questions
Write better with AI
Enhance any text you select on the desktop, on the web, in your editor or terminals.
Download PromptDC