Liner
FreemiumAI search and research assistant that highlights, saves, and synthesizes information from web pages and PDFs
What is Liner?
Liner (liner.com) is an AI-powered research assistant that combines web highlighting, document ingestion, AI-grounded search, and academic-style literature review into a single workflow. It began as a simple highlighter extension for the web — you could highlight text on any page and save it to a personal library — and in 2024–2026 has evolved into a dedicated research agent platform focused on scholars, students, and knowledge workers who need to find, read, and synthesize large amounts of source material.
The modern Liner product has three layers. The first is the Chrome/mobile highlighter that lets you mark and save passages from any webpage or PDF and organize them into collections. The second is Liner's AI search — a Perplexity-style answer engine that returns cited, synthesized responses from the web, but with academic-leaning source prioritization. The third is a growing family of specialized AI agents: Liner Scholar for literature review, Liner Write for drafting, Deep Research for multi-step inquiry, plus agents for PDF chat, file analysis, and research-gap identification.
What separates Liner from a pure search tool is the tight loop between highlighting, saving, and synthesizing. You can highlight passages across dozens of sources, then ask Liner to generate a literature review, a research gap analysis, or an annotated bibliography from those saved highlights. For graduate students preparing thesis chapters, researchers surveying a field, and consultants building briefs from lots of source material, that workflow is genuinely differentiating. It's less compelling if you just want a casual AI chat or general-purpose web search — pick ChatGPT or Perplexity for those jobs.
⚡ Quick Verdict
Students and researchers who want to highlight, save, and synthesize information across web pages and PDFs
Power users who need Perplexity-level search quality or enterprise research features
Free with limits. Premium $8.99/mo. Student discounts available.
Yes
Unique highlight-and-synthesize workflow for research
AI search quality trails dedicated AI search engines
Bottom line: Liner scores 4.1/5 — Students and researchers who want to highlight, save, and synthesize information across web pages and PDFs.
Liner Pricing
Free: 3 Advanced Searches per day, 3 Deep Research runs per month, limited file uploads, access to the Liner Basic model, and the standard highlighter extension. Enough to evaluate the product and do light casual research.
Pro — $14.99/month (billed annually) / $17.99 (monthly): Most popular tier. Unlimited Advanced Search, 25 Deep Research runs per month, 20 daily file uploads up to 100 MB each, ad-free experience, access across Liner, Liner Scholar, and Liner Write, and early access to beta features. This is the plan most active research users land on.
Max — $29.99/month (billed annually): Built for heavy researchers and professionals. Unlimited Advanced Search, 200 Deep Research runs per month, unlimited daily file uploads up to 200 MB per file, access to all AI models, no ads, and priority processing.
Team — $26.99/month per seat (billed annually): Max-level features plus a secure, dedicated team workspace with admin controls, member management, and collaborative highlight libraries. Best for research labs, consulting teams, and content agencies.
Annual billing saves roughly 20% versus monthly. Pricing verified on liner.com/pricing as of April 2026 — earlier reviews listed lower prices from prior pricing tiers, so always check the current plan page.
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Key Features
- Web and PDF highlighter — the original feature. Mark passages on any webpage or PDF, save them to collections, and reference them later. Works via browser extension on desktop and via mobile apps on iOS and Android.
- Advanced Search — Liner's AI answer engine returns cited, synthesized responses from the web. More academic-leaning source prioritization than generic AI search tools.
- Deep Research — multi-step research agent that breaks a question into sub-questions, searches multiple sources, and returns a structured report. Credited per run on paid plans.
- Liner Scholar — dedicated academic research agent focused on literature review, paper discovery, research gap analysis, and annotated bibliographies from saved highlights.
- Liner Write — academic and research-oriented writing assistant that references your saved highlights and generates drafts with integrated citations.
- File upload and PDF chat — upload papers or documents (up to 100 MB on Pro, 200 MB on Max) and chat with them, ask for summaries, or extract quotes.
- Multi-model AI access — Pro and Max unlock multiple frontier AI models rather than locking you to Liner's basic model.
- YouTube and video support — highlight and summarize video content with timestamp references.
- Personal knowledge base — saved highlights, notes, and research outputs persist in a searchable personal library that grows with your work.
- Cross-device sync — highlights and library sync across Chrome extension, web app, iOS, and Android.
Pros & Cons
Pros
- Unique highlight-plus-AI-synthesis workflow that no general-purpose AI search tool replicates
- Excellent for academic research, thesis prep, and literature review use cases
- Liner Scholar is a credible entry point into AI-assisted literature review
- Chrome extension integrates highlighting into normal browsing, not a separate workflow
- Multi-model access on paid plans removes the need for extra subscriptions
- Cross-device sync keeps highlights and library consistent across web and mobile
- Academic source prioritization makes Advanced Search better than generic AI search for scholarly questions
- Pro at $14.99/month (annual) is reasonable for the feature set versus dedicated research platforms
Cons
- Free tier limits (3 Advanced Searches/day, 3 Deep Research/month) are genuinely tight
- General-purpose AI search quality trails Perplexity for non-academic queries
- Less specialized than Elicit or Consensus for pure literature discovery
- Deep Research is rate-limited even on Pro (25/month) which can be constraining in heavy research phases
- Brand is shifting from "highlighter" to "AI research agents" which occasionally leaves the product feeling unfocused
- Mobile apps are less polished than the desktop web app
- Pricing has changed meaningfully in 2024–2026 — older reviews list outdated numbers, which is confusing
- Team plan limited in enterprise features compared to dedicated research platforms
Best For
- Graduate students preparing thesis chapters and literature reviews — the highlight-to-synthesis workflow plus Liner Scholar is tailor-made for surveying dozens of papers and drafting a literature review.
- Academic researchers running literature reviews, looking for research gaps, or tracking a field across many sources.
- Consultants and analysts who build briefings from large volumes of source material and need a personal knowledge base of highlights that persists across projects.
- Serious readers and lifelong learners who want to build a durable personal library of highlights and notes from online reading.
How Liner Compares
Against Perplexity, Liner is weaker on general AI search polish but adds a highlighter and a persistent library that Perplexity lacks. Against Elicit and Consensus, Liner is broader — it covers web sources plus highlighting plus writing — while Elicit and Consensus are specialists at peer-reviewed paper discovery and are stronger when your only need is literature search. Against Readwise for highlight management, Readwise is better at spaced-repetition review of highlights while Liner is better at AI synthesis of highlights. A common power-user setup is Liner for highlighting and literature review synthesis, Elicit or Consensus for paper discovery, and Perplexity for general web research — with the three tools covering different phases of a research project.
FAQ
What is Liner and who is it built for?
Liner is an AI research assistant that combines web highlighting, PDF chat, cited AI search, and specialized research agents (Liner Scholar for literature review, Liner Write for drafting, Deep Research for multi-step inquiry). It's built for people who read a lot and need to synthesize what they read — graduate students, academic researchers, consultants, analysts, and serious lifelong learners. The sweet spot is anyone who finds themselves highlighting passages across dozens of sources and then struggles to turn those highlights into a coherent literature review, briefing, or draft. Liner's workflow is explicitly designed for that loop.
Is Liner free, and what do the paid plans unlock?
Yes, Liner has a free plan with basic highlighting, 3 Advanced Searches per day, and 3 Deep Research runs per month. That's enough to evaluate the product but tight for real research work. Pro ($14.99/month annual) unlocks unlimited Advanced Search, 25 Deep Research runs per month, 20 daily file uploads up to 100 MB, ad-free access, and all three Liner products (Scholar, Write, and main). Max ($29.99/month annual) adds unlimited file uploads, 200 Deep Research runs per month, and access to all AI models. Teams get a dedicated workspace at $26.99 per seat. Verify current pricing on liner.com/pricing as it has changed several times in the past year.
How is Liner different from Perplexity and ChatGPT?
All three generate answers from web sources with citations, but their focus differs. Perplexity is a general AI search tool — fast, polished, and designed for quick answers and follow-up questions. ChatGPT is a general assistant that can search the web when asked. Liner is narrower and deeper: it's designed around the research workflow of highlighting passages, building a library, and synthesizing literature reviews or drafts from your saved highlights. If you want a daily AI search assistant, Perplexity wins. If you want a tool that supports the end-to-end research lifecycle from reading to drafting, Liner is the more purpose-built choice. Many serious researchers use both.
What is Liner Scholar and how does it help with literature review?
Liner Scholar is Liner's dedicated academic research agent. It helps with the specific tasks of literature review: finding relevant papers, summarizing them, building an annotated bibliography, identifying research gaps, and synthesizing findings across multiple sources. Unlike a generic AI chat, Liner Scholar is tuned to academic source quality and can reference the highlights you've saved in your personal library. The workflow is: highlight passages from papers you read, save them to a topic-specific collection, then ask Liner Scholar to draft a literature review that references your saved highlights. It doesn't replace reading the papers yourself, but it dramatically speeds up the synthesis phase.
Does Liner work with YouTube and PDFs?
Yes to both. For YouTube, Liner can highlight and summarize video transcripts, extract timestamped key points, and save video highlights to your library alongside web and PDF highlights. For PDFs, you can upload papers (up to 100 MB on Pro, 200 MB on Max), highlight passages, ask questions about the document, and save quotes with automatic source references. PDF chat works on scanned papers too as long as the text is machine-readable. For image-heavy or math-heavy papers, PDF chat quality will vary — that's a limitation of current AI models, not Liner specifically.
What is Deep Research and how is it different from regular search?
Deep Research is Liner's multi-step research agent. Instead of answering a single query from a handful of sources (what regular Advanced Search does), Deep Research breaks your question into sub-questions, searches multiple sources for each, synthesizes the findings, and returns a structured report. It's similar in concept to Perplexity's Deep Research or ChatGPT's deep research mode. Each run is credit-rate-limited even on Pro (25 per month), so save it for real research questions rather than casual queries. The output is noticeably more comprehensive than a single-shot search and is often a good starting point for a briefing or literature review.
Does Liner have a browser extension and mobile apps?
Yes. Liner has a Chrome extension that adds highlighting and AI search directly to any webpage or PDF you view in the browser — this is the primary capture surface for most users. It also has iOS and Android apps so you can highlight, search, and access your library on mobile. Highlights sync across all devices through the cloud, so a passage you save on your phone is available in the desktop web app and vice versa. The desktop web app is the most polished experience; mobile apps are functional but lag behind the desktop for complex research tasks.
Score based on product quality, usability, value, features, reliability, integrations & market trust. How we score →
📋 Good to know
Install the Chrome extension for web highlighting. Create an account for AI search and knowledge base features. Mobile apps available.
Highlights and searches are stored in the cloud for cross-device sync. Student data handling follows standard practices. Delete account to remove all data.
Upgrade to Premium ($8.99/mo) when you hit free tier limits on AI searches and highlights. Student discounts make this more affordable.
Very low. Highlighting is intuitive. AI chat works like other chatbots.