Liner

Liner is a South Korean AI company offering a suite of citation-first AI agents for professional and academic knowledge work, spanning search, academic research, and writing. It began in 2015 as a simple web highlighter — letting people mark up text on web pages and PDFs and add notes — and spent nearly a decade building a large, human-curated dataset of highlights, summaries, and notes before launching its AI Search Agent in 2023, which uses that curated dataset, rather than training indiscriminately on the open web, to filter for higher-value information. The company was founded by CEO Jinu "Luke" Kim and Brian Chanmin Woo, and is headquartered in Seoul, South Korea. In October 2024 it raised a Series B round widely reported at 270 billion won (about $200 million), led by Atinum Investment and Intervest with Samsung Venture Investment and LB Investment also participating — a few smaller-figure reports of the same round exist in press coverage, but the currency conversion is most consistent with the $200 million figure. Around the time of the round, the company said it served 10 million users across more than 220 countries.

The product line spans three purpose-built tools sharing one subscription: Liner (Search) augments regular web search with cited, fact-checked AI answers drawn from a stated index of over 200 million sources, plus a follow-up chat and a "Mind Map" visualization for exploring a complex topic; Liner Scholar focuses on academic workflows — finding and comparing papers, building citations, and generating literature reviews; and Liner Write assists with drafting emails, newsletters, reports, and essays (in formats like APA, MLA, or Chicago), integrating search directly into the writing interface and able to learn a user's tone from previously uploaded writing. Liner is available as a browser extension (Chrome, Edge, Safari) as well as native apps for iOS, Android, Mac, and Windows, and also offers an API for developers.

1. Install the Liner browser extension (Chrome, Edge, or Safari) or download the mobile/desktop app, and create a free account — no payment required to start.
2. Highlight any passage on any web page or PDF to get an inline AI explanation, summary, or expansion, building a personal library where every highlight, search, and question stays linked together.
3. Search directly in Liner (or through Google search results, where Liner injects a cited AI answer) using General mode for the open web or Scholar mode to search specifically across academic papers.
4. For a broad or unfamiliar topic, generate a Mind Map to visualize how the concepts you're researching relate to each other.
5. Switch to Liner Write when you need to draft something — an email, newsletter, report, or academic essay — with search and citation tools available in the same editor, and your own previously uploaded writing used to match your tone.
6. Upgrade from Free to Pro, Max, Team, or Enterprise as you need more daily search/file-upload volume, access to more AI models (ChatGPT, Gemini, Claude), or team-level billing and governance.

• Getting a cited, fact-checked answer to a research question instead of an unverified AI summary, with direct access back to the original sources.
• Academic literature review work — finding and comparing papers, managing citations, and generating a structured review — via Liner Scholar.
• Highlighting and annotating web pages and PDFs while researching, with an AI able to explain or summarize any highlighted passage in place.
• Drafting professional or academic writing (emails, reports, newsletters, essays in APA/MLA/Chicago format) with search and citation tools built into the same editor, matched to a user's own writing tone.
• Visualizing a complex or unfamiliar topic as a Mind Map to see how underlying concepts connect before writing about it.
• Developers integrating Liner's search and citation capabilities into their own tools via its API.