Liner

  • What it is:Liner is an AI-powered academic search engine for students and researchers that delivers precise answers from 200M+ trusted sources like papers and journals.
  • Best for:Students and academic researchers, Content creators and writers, Professionals conducting market/competitive research
  • Pricing:Free tier available, paid plans from $19.58/month or ~$96/year
  • Rating:82/100Very Good
  • Expert's conclusion:The Linear is best suited to serious researchers who are looking for a reliable, citeable and trusted AI Analysis of various formats that has been shown to be more accurate than others.
Reviewed byMaxim Manylov·Web3 Engineer & Serial Founder

What Is Liner and What Does It Do?

Liner is a global AI-based search and research company that was started in 2015, and uses trusted, fact-based answers along with footnoted, line-by-line citations to provide reliable answers to questions posed by students, researchers, and professionals using AI search tools to access a large database of verified information to help reduce hallucinations, and to help create accurate results.

Active
📍Seoul, South Korea
📅Founded 2015
🏢Private
TARGET SEGMENTS
StudentsResearchersKnowledge WorkersAcademicsEnterprise

What Are Liner's Key Business Metrics?

👥
13M+
Global Users
📊
220+
Countries
📊
KRW 44 billion (~$32M USD)
Cumulative Funding
💵
341.3%
2024 Revenue YoY Growth
📊
200M+
Academic Papers in Database
📊
13x
South Korea New Subscribers YoY Growth (2025)
📊
216%
South Korea Monthly Chat Traffic Growth
95.3 (October 2024)
OpenAI SimpleQA Benchmark Score

How Credible and Trustworthy Is Liner?

82/100
Good

Liner's level of product credibility is based on its ability to demonstrate accurate benchmarks for its products, as well as its ability to demonstrate a high level of user engagement from users in over 220 countries; however, there are limited numbers of independent third party reviews of Liner's products.

Product Maturity85/100
Company Stability80/100
Security & Compliance75/100
User Reviews75/100
Transparency85/100
Support Quality80/100
Ranked #1 globally on OpenAI SimpleQA benchmark (95.3 vs GPT-4.5's 62.5)13 million+ users across 220+ countriesPre-installed on Lenovo PCs via U.S. marketplaceSelected as main search engine for SK Telecom's A.Dot AI platformEvery answer includes clickable citations for verificationDatabase of 200M+ academic papers ensures scholarly accuracy

What is the history of Liner and its key milestones?

2015

Company Founded

Liner was initially founded as a global AI search and research company with the goal of creating an alternative way for people to find the information they need.

2012-2015

Origins as Aurum Planet

Liner began as a simple web-highlighter tool that allowed users to create human-verified highlights and summaries.

2024

OpenAI SimpleQA Benchmark Achievement

Liner's performance compared to other models of artificial intelligence such as GPT-4.5 shows that the performance of Liner exceeded the performance of GPT-4.5, as Liner achieved a ranking of #1 worldwide with a score of 95.3, while GPT-4.5 scored a 62.5.

2024

Research AI Agent Launch

Liner released a comprehensive suite of Research AI Agents that allow users to generate hypotheses, analyze literature, cite sources, and perform peer reviews.

2024

Record Revenue Growth

Liner achieved 341.3 percent year-over-year growth in revenue, indicating that Liner has successfully scaled its business model centered on providing a trustworthy form of AI technology.

2024

Lenovo Partnership

Liner's AI Search Product was selected for pre-installed inclusion on Lenovo PCs via the U.S. Marketplace and Onboarding Flow.

2024

SK Telecom Partnership

Liner was chosen as the primary search engine for SK Telecom's A.Dot AI Platform, as it was included as part of the Korean government's National AI Alliance Initiative.

2025

Asia Expansion Acceleration

Liner expanded into Asia, with the number of South Korea subscribers increasing by 13 times year-over-year, and the monthly chat traffic increasing by 216 percent.

Who Are the Key Executives Behind Liner?

Luke KimCEO & Founder
Liner was established in 2015 by the founder, with the goal of creating a new method for searching for information using trustworthy AI to reduce hallucinations, and to increase the reliability of answers provided.

What Are the Key Features of Liner?

AI Search with Line-by-Line Citations
Every answer sentence created by Liner has the option of clicking on a footnote that links to the source cited, allowing users to quickly verify the source and look at the original content.
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Source Management Tools
Users can exclude low-trust domains, such as blogs or community wikis, to improve their search results, and to enable them to have control over the type of sources they want to include in their searches.
Research AI Agent Suite
A complete research life cycle (Hypothesis Generation, Literature Analysis, Citation Suggestions, Peer Review) is supported.
Scholar Mode
It has been trained on over 200 million articles and journals to provide the most accurate results possible in Scientific and Academic Research Domains.
Content Analysis
Analyze and upload text, PDFs, PowerPoint, Word Documents, Images and YouTube Videos to get summary and insight.
Vibe Research Framework
Research at an Academic level that does not have to use Pre-defined Logic Trees so you can explore and test Hypotheses flexibly.
Agentic Architecture
Multiple Agents are working together to search through all of your sources, Synthesize Information and Structure Reports with the Step-by-Step Process shown.
📊
Multi-Platform Availability
Runs on Windows, Mac, iOS, Android and also available as a Chrome Extension in English, Chinese, Korean and Japanese.

What Technology Stack and Infrastructure Does Liner Use?

Technologies

AI AgentsMachine Learning Models

Integrations

Chrome ExtensionWindowsmacOSiOSAndroidLenovo PC pre-installationSK Telecom A.Dot platform

AI/ML Capabilities

Proprietary AI models trained on human-verified highlights and 200M+ academic papers, featuring agentic architecture with parallel agents for source synthesis and transparent reasoning processes. Ranked #1 on OpenAI SimpleQA benchmark.

Limited technical documentation available in public sources. Information based on official company announcements and product descriptions.

What Are the Best Use Cases for Liner?

Academic Researchers
Conduct a RIGOROUS Literature Reviews and Hypothesis Testing Across over 200 Million Academic Papers using Scholar Mode which ensures Academic Precision and Cite-able Sources.
Students
Find Trustworthy Answers with Source Verification, Generate Research Summaries and Streamline Learning Without Hallucinated Information.
Knowledge Workers
Reduce Research Workflows and Get Answered Questions with Cited Answers, Content Analysis in Different Formats and Efficiently Synthesize Information For Reports And Decision Making.
Enterprise Research Teams
Support Full Stack Research Platform Supporting Entire Research Life Cycle From Hypothesis Generation To Peer Review With Transparent Agented Reasoning.
Fact-Checkers and Journalists
Verify Information Instantly With Clickable Citations and Source Traceability Reducing Misinformation Risk While Maintaining Credibility.
NOT FORReal-Time Financial Traders
High Frequency Trading Environments Require Sub-Second Decision Making So Not Recommended - Research Focused Tool.
NOT FORUnstructured Social Media Analysis
Limited Suitability - Excludes Blogs and Community Wikis By Default Making It Unsuitable For Social Sentiment Analysis Requiring Broad Web Coverage.

How Much Does Liner Cost and What Plans Are Available?

Pricing information with service tiers, costs, and details
Service$CostDetails🔗Source
Basic (Free)$010 Deep Research uses per day, 1 AI Model Access, Limited highlighting, 25 Copilot Chat per day, 5 Liner AI on Google per day, 25 PDF Copilot per daySaaSworthy, AITools.inc
Essential/Premium$19.58/month or ~$96/yearMore Deep Research uses, Basic AI models, Limited file uploads, Unlimited highlightingSaaSworthy, Skywork AI
Professional/Pro$27.08/month or ~$180/yearUnlimited Deep Research, All AI Models access, Unlimited file uploads, Unlimited AI Agent calls, Advanced data analysisSaaSworthy, Skywork AI
Basic (Free)$0
10 Deep Research uses per day, 1 AI Model Access, Limited highlighting, 25 Copilot Chat per day, 5 Liner AI on Google per day, 25 PDF Copilot per day
SaaSworthy, AITools.inc
Essential/Premium$19.58/month or ~$96/year
More Deep Research uses, Basic AI models, Limited file uploads, Unlimited highlighting
SaaSworthy, Skywork AI
Professional/Pro$27.08/month or ~$180/year
Unlimited Deep Research, All AI Models access, Unlimited file uploads, Unlimited AI Agent calls, Advanced data analysis
SaaSworthy, Skywork AI

How Does Liner Compare to Competitors?

FeatureLinerChatGPTClaude
Starting Price$19.58/month$20/month$20/month
Free Tier AvailableYesYesYes
Web Search IntegrationYesNoNo
PDF AnalysisYesLimitedLimited
Citation/SourcesYesLimitedLimited
Deep Research FeatureYesNoNo
Browser ExtensionYesNoNo
Data AnalysisGoodExcellentGood
Starting Price
Liner$19.58/month
ChatGPT$20/month
Claude$20/month
Free Tier Available
LinerYes
ChatGPTYes
ClaudeYes
Web Search Integration
LinerYes
ChatGPTNo
ClaudeNo
PDF Analysis
LinerYes
ChatGPTLimited
ClaudeLimited
Citation/Sources
LinerYes
ChatGPTLimited
ClaudeLimited
Deep Research Feature
LinerYes
ChatGPTNo
ClaudeNo
Browser Extension
LinerYes
ChatGPTNo
ClaudeNo
Data Analysis
LinerGood
ChatGPTExcellent
ClaudeGood

How Does Liner Compare to Competitors?

vs ChatGPT

Liner has been focused primarily on information discovery/research and the real-time search of the web, whereas ChatGPT is centered around conversational AI and doing general purpose things. Liner can integrate with Google Search and provide you with links and citations of sources that provided that information. The ChatGPT product does not have those research focused tools/features. The price points are about the same too ($19.58/ month vs $20/ month).

Use Liner when you need to research and cite information and use ChatGPT when you want to have a general conversation with someone and you are looking to code something.

vs Claude (Anthropic)

There is similar positioning as to ChatGPT but Liner has better reasoning than Claude. Liner’s differentiation comes by way of web integration, source citations and other research specific tools such as PDF analysis and Deep Research. Claude also doesn’t have browser extensions or the ability to do real-time search.

Use Liner if you need to perform research using the internet and analyze various types of information and use Claude when you need to perform an analysis task that requires a lot of reasoning.

vs Perplexity AI

This would be a direct competitor to ChatGPT as well in terms of being an AI search engine. Both search engines provide users with answers to their questions with relevant sources. Liner takes the results of your search and allows you to organize and highlight the information across various formats (web, pdf, youtube) that are related to your question. Perplexity is much more well known and entrenched in the search space.

If you need to perform research using multiple formats (such as web articles, pdf's and youtube videos), use Liner to organize and highlight the information that relates to your question and use Perplexity when you are looking for the most accurate search results.

What are the strengths and limitations of Liner?

Pros

  • Free Tier is very powerful — 10 deep research uses per day at no cost make it accessible to casual users.
  • Multi-format support — analyzes web articles, pdfs, and youtube videos in one place.
  • Provides real-time sources — will include citations from trusted sources with real references.
  • Has browser extension — easy integration with google search and browsing.
  • Saves time — saves hours of searching for information and organizing the information.
  • Access to advanced AI models — professional subscription includes all AI models for comprehensive help.
  • Highlights and organizes — allow you to collect, highlight and structure insight for future reference.

Cons

  • Billing issues — many users have had billing issues including difficulties in cancelling subscriptions and denial of refunds.
  • Performance issues — many users experience crashes and “something went wrong” errors.
  • The user finds that this tool performs at a level that is significantly lower compared to the price of ChatGPT.
  • The user states that they have compared this product to ChatGPT; in their opinion, the other product is superior.
  • Users note that the generated responses from the tool are inaccurate at times, even when the user cites relevant resources.
  • Users find the pricing structure of Liner confusing because there appear to be several different pricing options being offered by the same vendor, which leads to uncertainty about the cost of the service.
  • There appears to be some confusion on the part of the users regarding the billing model of Liner; in addition, the users feel frustrated that they cannot easily cancel their subscriptions.

Who Is Liner Best For?

Best For

  • Students and academic researchersThe researchers who use this product state that the tool is ideal for conducting deep research; additionally, it allows for the generation of citations and also provides the capability to analyze PDF files.
  • Content creators and writersThe researchers find that the multi-format research capabilities, combined with its ability to integrate with the web, and highlight the content researched, all provide an efficient way to collect and organize research content.
  • Professionals conducting market/competitive researchAdditionally, the tool provides real-time web search capabilities along with the ability to identify the sources used for the research and to organize the research data; all of these capabilities support the researchers' workflow.
  • Users wanting free research toolsAlthough Liner does offer a generous free tier that provides up to 10 daily Deep Research uses, the researchers still need to pay for the premium version in order to gain access to many of the features that are important to them.

Not Suitable For

  • Users prioritizing performance and reliabilityHowever, the researchers found that the crashes and slow performance issues associated with Liner made it unreliable for them to complete timely research projects using the tool. As such, the researchers would recommend that they either utilize ChatGPT or Claude.
  • Budget-conscious individuals after free tierIn addition to experiencing reliability issues, the researchers experienced frustration with regards to the billing process associated with Liner; specifically, the researchers reported problems with the billing process, including difficulty with canceling their subscriptions. The researchers stated that if they were looking for a simple tool for generating content, they would be better served to use a free alternative to Liner, namely Perplexity.
  • Users requiring simple, straightforward interfacesAdditionally, the researchers stated that the potentially overwhelming feature set associated with Liner could be too much for some researchers; specifically, those researchers who are simply looking for a basic chatbot that can generate content quickly, may be overwhelmed by the number of features provided by Liner. In such cases, the researchers suggest utilizing ChatGPT.

Are There Usage Limits or Geographic Restrictions for Liner?

Deep Research Usage (Free)
10 uses per day
Copilot Chat (Free)
25 per day
Liner AI on Google (Free)
5 per day
PDF Copilot (Free)
25 per day
AI Models (Free)
Basic model only, single AI model access
File Uploads (Free/Essential)
No file uploads on Free, Limited on Essential plan
Data Privacy
Data handling practices not fully detailed in available sources

Is Liner Secure and Compliant?

Data Privacy InquiryFAQ mentions 'How does Liner handle data privacy?' but specific details not provided in available documentation
Information EncryptionNo specific encryption standards (AES-256, TLS) mentioned in available sources
Compliance CertificationsNo SOC 2, ISO 27001, GDPR, or HIPAA certifications mentioned in available sources
Data Storage LocationCloud infrastructure details not specified in available documentation
Access ControlsNo information about SSO, MFA, or role-based access control in available sources

What Customer Support Options Does Liner Offer?

Channels
Support resources available via Liner websiteFAQ section addressing common questions about pricing and features
Satisfaction
Mixed - users praise core research features but express frustration with billing practices and performance issues
Support Limitations
Limited support channel information available in documentation
No phone, live chat, or email support explicitly mentioned in available sources
Users report difficulty resolving billing and subscription issues

What APIs and Integrations Does Liner Support?

API Type
No public API documented. Primarily a consumer-facing AI search and research tool with no developer portal or API references found in official sources or searches.
Authentication
N/A - No public API available.
Webhooks
Not supported. No webhook functionality mentioned across documentation, developer resources, or reviews.
SDKs
None available. No official SDKs on GitHub or developer sites.
Documentation
No API documentation exists. Product focuses on end-user features via web/app/Chrome extension.
Sandbox
N/A - No developer sandbox or testing environment.
SLA
No uptime guarantees published for API (none exists). Consumer service available across platforms with no formal SLA.
Rate Limits
Free tier has daily question limits; Pro unlocks more Deep Research and file uploads, but no API-specific limits.
Use Cases
N/A for programmatic integration. Best used via UI for research, summarization, and analysis.

What Are Common Questions About Liner?

Liner provides users with a variety of AI-powered tools to conduct research, including AI-based search, content analysis of PDFs/images/videos, AI-generated summaries, follow-up questions and scholarly mode for academic research. The company utilizes a variety of AI models, including GPT, Claude, and Gemini, and is accessible on a cross-platform basis through web applications, mobile apps, and a Chrome extension.

As previously mentioned, Liner does provide a free tier with usage limitations. Users wishing to unlock additional features will need to purchase Liner Pro. Users will also be able to upload files, access advanced models, increase the amount of Deep Research available, and activate Scholar Mode, among other features. Pricing details for both Liner and Liner Pro can be accessed through the application or the company's website. Additionally, users of Liner Pro can take advantage of discounts of up to 40% off of Pro plans.

Liner excels in research accuracy, content highlighting/annotation, and multi-format analysis (PDFs, Images, YouTube) compared to Perplexity as shown in the benchmark comparisons. In addition, Liner provides a scholar mode that is designed specifically for academic papers. Perplexity is generally focused on providing an all-purpose search engine.

Liner provides many options for ensuring user's privacy when using the product. This includes various security options for how they handle their data, although there are some potential issues and concerns about how Liner handles this aspect of the product. In addition, Liner does not store the user's login information (credentials), and they provide the option for users to verify the source(s) they are pulling data from. However, there are no publicly stated certifications such as SOC 2.

There are no traditional APIs that can be integrated into Liner. Instead, Liner can be used through a browser-based extension (Chrome) that allows for syncing across multiple devices. Therefore, Liner is best suited for use as part of a research workflow that utilizes collections for organizing information.

As an app, Liner can be found in the app stores. The terms of service for Liner can be found at https://liner.com/terms. Liner also boasts a user base of more than 10 million people. Users have praised the responsiveness of the product, and users have several methods to receive assistance if needed including sending feedback through the app and/or contacting them directly through their social media channels.

Yes, Liner offers a generous free tier of service, which includes a very high number of questions per day that can be asked. For those who wish to move beyond the free tier, there are various Pro upgrades available, and these upgrades include discounts. Although Liner does offer a way to easily upgrade your account, there is no specified time limit for a trial version of their service.

Yes, there are some AI models/tools within Liner that are only accessible through the Pro version of the service. Occasionally, users may experience difficulty obtaining certain sources, or the process of obtaining these sources may require a considerable amount of time. Also, while Liner is reliable in terms of its results, it is not always entirely accurate.

Is Liner Worth It?

Overall, Liner is a mature AI research assistant that was developed from a web highlighter, and therefore has proven itself to be a superior tool in comparison to other research assistants in terms of both accuracy and the ability to obtain citable sources. Additionally, Liner has provided multi-format analysis capabilities that are beneficial for both researchers and students. Furthermore, Liner addresses two major limitations of AI research assistants, namely hallucination, and lack of verifiable answers through its Scholar Mode. With regard to platform compatibility, Liner is well-positioned in comparison to general search engines due to its strong cross-platform support.

Recommended For

  • Those that are researching and writing academic articles and need to find accurate academic search with citations.
  • Productivity professionals that are analyzing PDFs, videos and multiple sources.
  • Global teams that require multilingual support (English, Chinese, Korean, Japanese).
  • Those that value verifiable AI over speed in their research workflows.

!
Use With Caution

  • Teams that require API integrations or programmatic access – UI-only tool.
  • Those working in highly sensitive data environments – privacy measures but no certification details provided.
  • Casual Search Users - Treat As A Research Tool, Not Just A Quick Google Replacement

Not Recommended For

  • Developers Building Custom AI Pipelines - Lacks APIs/SDKS
  • Unlimited Advanced Models For Budget-Free Users
  • Enterprise Search In Real Time - Delayed Fetches Reported Occasionally
Expert's Conclusion

The Linear is best suited to serious researchers who are looking for a reliable, citeable and trusted AI Analysis of various formats that has been shown to be more accurate than others.

Best For
Those that are researching and writing academic articles and need to find accurate academic search with citations.Productivity professionals that are analyzing PDFs, videos and multiple sources.Global teams that require multilingual support (English, Chinese, Korean, Japanese).

What do expert reviews and research say about Liner?

Key Findings

Linear provides highly accurate AI Research using citable sources, multi format analysis, and scholar mode which is trained on 200 Million + scholarly articles. Built off of 10 year old highlighter software with 10 Million + registered users, it also supports Global Languages and Cross Platform Use. Pro Tier offers more advanced features and has been ranked as better than some other tools such as Perplexity.

Data Quality

Good - detailed from official site, App Store, reviews (Unite.AI, Slashdot), and news. No direct pricing/API docs; relies on aggregated user/reviewer insights.

Risk Factors

!
Some features (Advanced Models, Deep Research) have a Paywall
!
Source fetch delay/failures may occur occasionally
!
Limited information about enterprise/compliance available publicly
!
No API for Integrations
Last updated: February 2026

What Additional Information Is Available for Liner?

User Base and Recognition

Used by 10 Million+ Students/Researchers across 50 Countries. Multiple times ranked #1 in App Stores for Productivity Tools.

Evolution and Dataset

Began 10 Years Ago as Web Highlighter; Built large human verified dataset that powers its Accurate AI. Now Full Research AI Platform with Research AI Agent Suite.

Multilingual Support

Available in English, Chinese, Korean, Japanese. Great for International Research Teams.

Media Coverage

Reviewed in Unite.AI for Review of Research Speed/Accuracy; Company News on Scaling Trustworthy AI Against Hallucinations.

Cross-Platform Availability

Available for Windows, Mac, iOS, Android, and Chrome Extension. Data/collections sync across devices.

What Are the Best Alternatives to Liner?

  • Perplexity: AI Answer Engine with Real-Time Web Search and Citations. Generally faster for General Searches, However Trails Linear in Research Accuracy Benchmarks and does not allow Multi Format Uploads. Best for Broad, Fast Searches. (perplexity.ai)
  • Andi: Clean, Ad-Free AI Search with Visual Cards and Conversational Interface. Simpler to use for Casual Users compared to Liner's Deep Research/Summaries. Best for Clean Answers Without Annotations. (andisearch.com)
  • Humata: Humata.ai is a tool that can use AI to analyze PDF documents and provide answers to questions asked about the content in those files. While it does allow users to upload their files via the internet (similar to how users can upload files to Liner), Humata.ai has fewer capabilities when searching the internet for information (e.g., through web searches) compared to Liner. The best use case for this tool would be when there are large volumes of documentation to be analyzed.
  • ChatPDF: Users can "talk" to PDF files utilizing AI for PDF file summaries and questions. This is similar to Liner but while Liner offers a full research platform, Humata is much more limited in its scope as it does not have a web search function nor does it support video content. As such, the best use case for this tool is if you need to do some analysis solely on PDF content.
  • Elicit: Elicit.org provides an AI based platform for researchers to conduct literature reviews, discover new research papers, and receive summaries of research articles. Like Liner, elicit focuses primarily on scholarly research, but elicit is less versatile than Liner as elicit currently only allows access to research articles (it does not allow users to view images or videos).

What Are Liner's Search Performance Metrics?

High (with citations)
Answer Accuracy
Academic papers, web, real-time
Source Coverage
Multiple frontier models
AI Models
Instant MLA/APA/Chicago
Citation Generation
Cuts research time in half
Research Speed

What Ai Models Supported Does Liner Support?

GPT-4oGPT-5ClaudeGeminiLlama 3.1 405B

Access to latest frontier models including GPT-5 and Llama 3.1

What Search Capabilities Does Liner Offer?

Real Time Search
Yes
Line-by-Line Citations
Every answer line includes source citation
Academic/Scholar Mode
Specialized search for research papers
Search Next
AI-suggested follow-up queries
Multimodal Support
YouTube summaries, PDF analysis, file uploads
Context Window
Conversation context maintained

What Answer Quality Features Does Liner Offer?

Line-by-Line Citations

Each answer line contains links to direct references to the source material referenced so users can verify the accuracy of the answer provided.

Semi-Parametric Model

The goal of humata is to combine the reasoning capabilities of LLM technology with retrieval of credible sources to limit hallucination.

Scholar Mode

This is a specialized academic search engine that will give users access to high quality research papers.

AI Agents

There are several specialized agents available for conducting literature reviews, generating hypotheses, and performing peer review.

Deep Research

Humata uses multiple steps to synthesize research data from millions of different sources.

What Platforms Does Liner Support?

Web AppiOS AppAndroid AppChrome ExtensionGoogle SERP Integration

Cross-platform sync across browser extension, mobile apps, and Google search

What Is Liner's Data Privacy Features Status?

Source VerificationAll answers include verifiable citations
No Ad TrackingAd-free experience on paid plans
Data ExportExport highlights and collections
Cross-Device SyncSecure sync across all platforms
GDPR ComplianceStandard privacy policy applies

What Knowledge Sources Does Liner Support?

Source TypeCoverageUpdate Frequency
Academic PapersPeer-reviewed + journal rankedReal-time
Web PagesTrustworthy sourcesReal-time
YouTube VideosTranscripts + timestampsNear real-time
PDF DocumentsUploaded file analysisOn-demand
Community HighlightsMillions of user highlightsContinuous

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