# Locus vs MARK•R

Locus records 615 monthly visits with -85.1% month-over-month growth and Freemium, Free Trial pricing. MARK•R records 43 monthly visits with -95.1% growth and Freemium pricing.

| Metric | [Locus](https://openaitools.app/tool/locus) | [MARK•R](https://openaitools.app/tool/mark-r) |
| :--- | :--- | :--- |
| Website URL | https://locusextension.com | https://mark-r.com |
| Categories | AI Copilot, AI Research Tool, AI Summarizer, AI Search Engine | AI Assistant, AI Copilot, AI Writing Assistants, AI Research Tool |
| Pricing Model | Freemium, Free Trial | Freemium |
| Monthly Visits | 615 | 43 |
| MoM Growth Rate | -85.1% | -95.1% |
| Primary Market | United States | Global |
| Direct Visits | 239 | 16 |
| Review Score | 4.1 | 4.2 |
| Saved Count | 3 | 0 |
| Supported Platforms | Website | Website |

## Locus

Locus reframes the browser search box around intent rather than exact text. Regular Ctrl+F only finds the words you already know; Locus uses natural-language processing so you can ask for a concept, a section, or an answer and be taken straight to the matching part of a page or PDF. This makes it particularly useful for long papers, dense textbooks, and news articles where you know what you want to learn but not the phrasing used on the page.

Beyond finding text, Locus layers AI assistance on top of what you read. Its AI helpers summarize pages or passages, generate note cards for study, and suggest follow-up research topics, drawing on current large language models such as OpenAI GPT-4o and 4o mini, Anthropic Claude 3 Haiku, and Google Gemini 1.5 Flash. You can also bring your own OpenAI API key to unlock unlimited usage.

Locus is built as a lightweight browser extension with a companion dashboard. A generous free tier covers personal reading and research, while a Professional plan removes document and action limits for heavier users. Reviews from students, analysts, and research assistants highlight its value in quickly narrowing long-form content down to the parts worth reading.

**Pricing & Plans:** Free plan at $0 forever with daily document and AI-action limits; Professional plan at $7.50/month billed annually ($90) or $9/month with advanced AI models, faster processing, and no document limits, including a free trial.

- **Natural-language smart search:** Use everyday language to find the exact section you need on any web page or PDF, catching matches that exact keyword search cannot.
- **AI summarization:** Summarize entire pages or selected portions to save time and get the key takeaway quickly.
- **Research and study helpers:** Locus AI helpers brainstorm research topics, suggest further reading, and generate note cards to help you retain information.
- **Multiple LLM backends:** Choose from current models including OpenAI GPT-4o-family options, Anthropic Claude, and Google Gemini, with new releases added within days.
- **Favorites and search history:** Save key search answers and passages to favorites so you can return to them across long papers and documents.

**Strengths:** Makes long PDFs and web articles searchable by meaning, not just keywords; Combines search, summarization, and study tools in one extension; Free tier is genuinely usable for personal research; Supports multiple leading LLM providers and bring-your-own API key

**Limitations:** Free plan caps searches and AI actions per day; Advanced models and no-limit usage sit behind the paid tier; Some AI features require bringing your own OpenAI API key for unlimited use

[Profile (Markdown)](https://openaitools.app/tool/locus.md)

## MARK•R

MARK•R is a browser plugin built around one interaction: highlight text, then talk to it. Instead of copying a passage into a separate chatbot, you select it on the page and a small icon appears with an AI input field. Whatever you ask is answered inline, in the flow of reading, which keeps the source material and the conversation in the same visual context.

The distinguishing design decision is that MARK•R does not restrict itself to the highlighted fragment. It reads the surrounding page as well, so questions can be about the wider argument, the definitions used elsewhere in the article, or the assumptions behind a claim. That makes it more useful for interpretation and analysis than a simple selected-text rewriter, and it is the reason the plugin is marketed for research, study and content development rather than only for editing.

Practical applications cluster around comprehension and production. Students and researchers use it to unpack difficult concepts and terminology; professionals use it to clarify technical, legal or medical language; writers and marketers use it to generate summaries, outlines and alternative phrasing; and anyone drafting email in a browser can highlight the message they received and ask for suggested replies. Access is tiered: a free plan with a modest daily allowance of GPT-3.5 calls, paid Standard and Pro plans that add higher limits and GPT-4, and custom builds for organisations. The published plan structure references GPT-3.5 and GPT-4, so newer model options may not be available on this tool.

**Pricing & Plans:** Freemium. A free tier provides 15 calls per day, 2,000 highlighted characters, 500 characters of prompt input, GPT-3.5 and 1,000 output characters. Standard is $8 per month and Pro is $12 per month, adding higher daily call limits, larger character allowances, longer output and GPT-4 access (one GPT-4 call equals 20 GPT-3.5 calls). Custom builds are available for organisations and enterprises.

- **Highlight-to-ask interaction:** Selecting any passage on a page activates a dynamic icon and AI prompt field, so a question can be asked at the exact place you are reading rather than in a separate chat window.
- **Whole-page context:** Responses draw on the surrounding article or page, not just the highlighted fragment, which supports deeper questions about argument, terminology and implications.
- **Inline content generation:** Ask for an executive summary, a white-paper outline, slide talking points, suggested email replies or rewritten copy without leaving the browser.
- **Comprehension support:** Explain difficult terms, unpack technical or legal jargon and request simpler phrasing, which helps with dense academic, medical and financial material.
- **Tiered daily allowances:** Free, Standard and Pro plans set different daily call limits, character allowances, output lengths and model access, with custom enterprise builds available.

**Strengths:** Works inline on any page, so you never have to copy text into another tool; Uses the whole page as context, not just the highlighted passage; Low entry price with a genuinely usable free tier and clear plan differences; Broad range of applications from study and research to summaries and email replies

[Profile (Markdown)](https://openaitools.app/tool/mark-r.md)

## Frequently Asked Questions

### How do Locus and MARK•R compare in monthly traffic?

Locus has 615 monthly visits, while MARK•R has 43. Traffic estimates describe audience size, not product quality.

### How do their growth rates compare?

Locus has a month-over-month growth rate of -85.1%; MARK•R has -95.1%.

### How does pricing compare?

Locus: Freemium, Free Trial. Free plan at $0 forever with daily document and AI-action limits; Professional plan at $7.50/month billed annually ($90) or $9/month with advanced AI models, faster processing, and no document limits, including a free trial. MARK•R: Freemium. Freemium. A free tier provides 15 calls per day, 2,000 highlighted characters, 500 characters of prompt input, GPT-3.5 and 1,000 output characters. Standard is $8 per month and Pro is $12 per month, adding higher daily call limits, larger character allowances, longer output and GPT-4 access (one GPT-4 call equals 20 GPT-3.5 calls). Custom builds are available for organisations and enterprises.

## Alternatives

| # | Tool Name | Monthly Visits | MoM Growth Rate | Pricing Model | Summary | Profile (Markdown) |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | [Perplexity](https://openaitools.app/tool/perplexity-ai) | 88,310,223 | -3.7% | Freemium | Real-time AI answer engine and research workspace combining live web citations with frontier reasoning models. | [.md](https://openaitools.app/tool/perplexity-ai.md) |
| 2 | [Monica](https://openaitools.app/tool/monica-ai) | 4,512,775 | -11.3% | Freemium | All-in-one AI assistant across web, browser, desktop and mobile | [.md](https://openaitools.app/tool/monica-ai.md) |
| 3 | [SciSpace](https://openaitools.app/tool/scispace) | 4,464,111 | +8.6% | Freemium | AI research platform for reading, understanding and writing scientific papers | [.md](https://openaitools.app/tool/scispace.md) |
| 4 | [Sider](https://openaitools.app/tool/sider) | 2,644,740 | -10.6% | Freemium | AI sidebar and browser agent for reading, writing and research | [.md](https://openaitools.app/tool/sider.md) |
| 5 | [Merlin AI](https://openaitools.app/tool/merlin-ai-plugins) | 1,382,634 | +13.1% | Freemium | One AI assistant that plugs ChatGPT, Claude and Gemini into every tab | [.md](https://openaitools.app/tool/merlin-ai-plugins.md) |
| 6 | [Merlin AI](https://openaitools.app/tool/merlin-ai) | 1,382,634 | +13.1% | Freemium | One-click AI assistant for browsing, writing and research | [.md](https://openaitools.app/tool/merlin-ai.md) |
| 7 | [ChatPDF](https://openaitools.app/tool/chatpdf) | 1,044,477 | -3.7% | Freemium | Chat with any PDF, video, or website and get cited answers in seconds | [.md](https://openaitools.app/tool/chatpdf.md) |
| 8 | [Glasp](https://openaitools.app/tool/glasp) | 889,564 | -14.1% | Freemium | Highlight the web, learn in public, and build your AI clone | [.md](https://openaitools.app/tool/glasp.md) |
| 9 | [HARPA AI](https://openaitools.app/tool/harpa-ai) | 537,461 | +99.3% | Freemium | One browser agent that combines every major AI model with web automation | [.md](https://openaitools.app/tool/harpa-ai.md) |
| 10 | [Glarity](https://openaitools.app/tool/glarity-summarize-google-and-youtube) | 188,823 | -49.6% | Freemium | Summarize YouTube, Google, and any page with AI — free in your browser | [.md](https://openaitools.app/tool/glarity-summarize-google-and-youtube.md) |

---
Source: https://openaitools.app/compare/locus-vs-mark-r

More Markdown: [Categories](https://openaitools.app/categories.md) · [Traffic rankings](https://openaitools.app/rankings.md) · [llms.txt](https://openaitools.app/llms.txt)