Liner sells a simple promise in a noisy market: an answer you can check. Where general chatbots produce fluent text and search engines return a wall of links, Liner tries to sit in the gap - reading across academic papers, authoritative publications, and vetted web pages, then handing back a response with the citations still bolted on. Its tagline, "search without doubt," is aimed squarely at the people for whom a wrong answer has consequences: students, researchers, and the widening class of knowledge workers who research for a living.
The company did not start as an AI project. In 2012, Jinu Kim was a sophomore at Yonsei University in Seoul who had already tried his hand at a Facebook page business. Liner was, by his own telling, a third venture. In 2014 he moved to Silicon Valley with roughly $40,000 and a modest idea: a browser tool for highlighting text on the web. It shipped in 2015 and did something unglamorous but valuable - it collected, highlight by highlight, a record of what millions of readers considered worth marking.
The turn came in 2020. When GPT-3 arrived, Kim's read was that if a machine could reliably read and answer on a person's behalf, the entire search experience would shift. Liner reoriented around AI-driven search, and the years of highlight data became more than a feature backlog - they became a signal for ranking how reliable a given document is. That decade of behavior is now part of how Liner decides which sources to surface.
What you can actually do with it
At its center is Liner's AI search, which answers questions with cited responses. Around it sits a family of tools. Liner Copilot, the direct descendant of that original highlighter, lives in the browser and lets you highlight, ask, and summarize across web pages, PDFs, and YouTube videos - useful when the source is a 40-minute lecture or a dense report. Liner Scholar targets academic work such as literature review and citation recommendation. Liner Write turns research into source-backed drafts. And a set of Research Agents handles more agentic jobs like hypothesis generation and peer-review support.
For a student, that can mean turning a reading list into a defensible set of citations. For an analyst, it can mean compressing a first pass of research from an afternoon into a couple of minutes. Liner claims its proprietary SearchLLM completes research tasks in under two minutes, against the three-to-thirty-minute range it attributes to rivals - a gap that, if it holds, matters most to anyone working against a deadline.
Who is paying for it
Liner's audience is unusually global for a company its size. It reports roughly 12 million monthly active users across more than 220 countries, with over 90% of them outside South Korea and about 60% of paid subscribers based in the United States. The business runs on a freemium model: a free Basic tier funnels toward paid plans, with Research Agents increasingly doing the monetization work and an expansion underway into B2B sectors like finance, management, and commerce, plus an API for developers.
The money has followed. In October 2024 Liner raised a $29M Series B led by InterVest and Atinum Investment, with Samsung Venture Investment and LB Investment among the participants, bringing reported cumulative funding to roughly $36.4M. Alongside the round, the company traded its old getliner.com address for the premium liner.com - a small move that reads as a statement of intent for a firm that spent a decade as a browser add-on and now wants to be a destination.
The company it keeps
Liner is competing in the most crowded room in software. Perplexity, Google's AI Overviews, and ChatGPT's search all want the same query. Liner's answer is not to out-scale them but to out-focus them: pick a lane - students, researchers, knowledge workers - and make transparent citation the default rather than an afterthought. It has also drawn notice for capital efficiency, reaching millions of users on comparatively lean funding, and joined an SK Telecom-led consortium to build a sovereign AI foundation model in Korea. In 2025, Kim landed on Forbes' 33 AI Founders to Watch. The bet underneath all of it is that when the answer actually matters, people will choose the tool that shows its work.