Cline

Open source AI programming assistant, the choice of 5 million developers, with zero price increase and only API cost

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Cline is an open source AI programming assistant that was launched in 2024. With its unique positioning of being completely open source, flexible model (BYOK), zero markup and only charging API cost, it has quickly gained the favor of more than 5 million developers. As of April 2026, Cline has received more than 60,500 stars on GitHub, making it one of the most popular AI programming extensions in the VS Code ecosystem. Unlike closed-source solutions such as Cursor and Windsurf, Cline allows developers to fully control AI model selection and supports multiple providers such as Anthropic, OpenAI, Google, DeepSeek, and Ollama local models. It also supports MCP (Model Context Protocol) and can create custom tool extensions. Its core advantages lie in high flexibility and cost transparency, but there are also barriers such as no inline completion and complex settings. It is more suitable for developers with strong technical capabilities and the pursuit of model freedom.
Cline is maintained by an independent development team and is a completely open source project. The source code is hosted on GitHub (github.com/cline/cline), and the community is extremely active. The core concept of the project is "Open Coding Agent" - to create an open source version of Cursor, making AI a real programming agent rather than a simple completion tool. Cline was officially launched in 2024 and was initially released as a VS Code extension. With the rapid growth of functions and user scale, it currently supports multiple platforms (VS Code, CLI, JetBrains IDE) and has become an important player in the field of AI programming assistants. A supply chain security incident (OpenClaw tampering incident) occurred in February 2026, but the team responded promptly and repaired it, further improving security. Cline is positioned as an "open source AI programming assistant" and its core differentiated advantages include: completely open source (code is transparent and auditable), BYOK (bring your own key, no vendor lock-in), cost transparency (real-time display of API consumption), and MCP support (standardized protocol extension). The target user group is developers with strong technical capabilities who value freedom of model selection and cost control.
Understand: Developers can ask any questions about file structure, dependencies, code behavior, etc., and Cline will analyze the entire code base to give accurate answers. Refactor: Coordinate modifications in large code bases, automatically maintain consistency in imports, types, and behaviors, and are suitable for large-scale code transformation. Automated execution (Automate): realize automation in scripts, scheduled tasks and CI/CD pipelines through Cline CLI, supporting headless browser testing, screenshots and other capabilities. Cline currently supports three major platforms: Visual Studio Code extension (distributed through VS Code Marketplace and Open VSX), Cline CLI (command line interface, which can be integrated into scripts and CI/CD), and JetBrains IDE (IntelliJ IDEA, PyCharm, WebStorm, etc.). Cline supports multiple AI model providers, providing significant flexibility advantages. In terms of cloud models, it supports Anthropic (Claude series), OpenAI (GPT series), Google Gemini, Mistral, DeepSeek and other mainstream models. In terms of local models, Ollama supports fully localized model deployment. This multi-model architecture allows developers to choose the most appropriate model based on task characteristics and cost budget - the cost-effective Sonnet or Gemini can be selected for daily use, and the Opus-level model can be switched to for complex tasks. Cline version 4.0 introduces native support for MCP (Model Context Protocol), a standardized protocol that allows the creation of custom tool extensions and connection to external services such as databases, APIs, and GitHub, greatly expanding the capabilities of AI programming assistants. Cline adopts the "Human-in-the-Loop" design concept, and each operation requires user approval before execution. The interface will display the change difference view (diff), allowing users to clearly understand what modifications the AI will make. This design improves security while retaining efficiency advantages—much faster than purely manual coding, but the final decision rests with humans.
Cline itself is completely free, and developers only need to pay for the API they use. This is in sharp contrast to closed source solutions such as Cursor ($20/month Pro version), Windsurf ($20/month), Claude Code ($20/month Max version). Cline is known as a "zero markup" product, charging only the cost of API calls and no additional fees. The cost is completely transparent, and the interface will display the token consumption and cost accumulation of each task in real time. The daily cost of an Opus-level model for heavy use is about $10-20, and it can be controlled to a lower level if you use Sonnet or Gemini Pro. This model is suitable for cost-conscious developers, but there are certain barriers to users with limited budgets. Cline provides an enterprise version (Contact Sales), which is suitable for team deployment and management needs.
Judging from user feedback, Cline's core advantages are widely recognized: first, the model is highly flexible, and users can freely switch between different models according to task characteristics, and test and compare the effects of each model at any time; second, the cost is transparent, with real-time display of costs and token consumption, which facilitates budget control; third, open source and scalable, The code is completely transparent, the community is highly active, and new model support is usually implemented within a few days after release; fourth, efficiency is significantly improved, and automatic code generation and command execution greatly improve development efficiency. Some users even said that "Cline is not only an AI programming assistant, but also a co-developer, Google, and Stack A combination of Overflow". The main concerns of users include: complex settings, the need to obtain API keys and configure providers by themselves, and there is a certain threshold for novices in AI tools; no inline completion, Cline is not an automatic completion tool but a task execution mode, and there is no tab completion function; variable cost risks, no fixed subscription may lead to rapid accumulation of costs during heavy use, requiring users to set spending limits by themselves. Some users mentioned that Cursor is more professional in handling complex programs, while Cline is more suitable for scenarios that require full control of models and expenditures. Domestic developers generally recognize Cline's open source and flexibility, but are also concerned about configuration convenience and local model support. Some users pointed out that Cline is the "open source version of Cursor", allowing AI to truly become a programming agent rather than an auxiliary completion tool. Minority's in-depth evaluation believes that Cline "revolutionarily opens a new era of AI-assisted programming", has a friendly interface, powerful functions, and is suitable for developers of all levels.
The professional evaluation website BuildFastWithAI pointed out in its March 2026 evaluation that Cline is "one of the most noteworthy open source AI programming agents in 2026." The reasons for recommendation include BYOK mode, model flexibility, MCP support, community activity and other dimensions. CSDN's Hengping article compared Cline with Continue and Claude Code and believed that Cline has "the most complete functions and richest support" among open source solutions. The title of Minority's in-depth review article is directly positioned as "A New Era of AI Programming Assistants", recognizing its revolutionary positioning. The current AI programming assistant market presents a differentiated competitive landscape: Cursor is positioned as an "AI native IDE" with the smoothest experience but the highest price ($20/month closed source); Windsurf is positioned as an AI Agent IDE, similar to Cursor's positioning; Claude Code is positioned as a terminal agent, which is highly user-friendly but only supports Anthropic models; Cline is positioned as an open source and flexible solution, free but requires self-prepared API; Aider is another option for end users. Many media believe that 2026 is a critical year for AI programming assistants, as the tool has evolved from an "early adopter toy" to a "full-stack development agent." Industry observers believe that AI programming assistants are showing several important trends: the evolution from completion to Agent (from Copilot's assisted completion to Agent's autonomous execution); the rise of MCP standardized protocols (similar to API standardization in the server era); flexible combination of multiple models becoming mainstream (selecting the most suitable model based on the task rather than a single solution); security and supply chain security are receiving more attention (Cline's February 2026 supply chain attack triggered widespread discussion).
In February 2026, a supply chain security incident occurred at Cline. Cline CLI version 2.3.0 was found to have been tampered with to silently install a self-hosted AI agent called OpenClaw. This incident attracted widespread attention from the developer community, and security public accounts such as RASSec published articles specifically for analysis. Officials promptly issued announcements explaining the situation and providing repair plans. This incident reminds developers that even open source tools need to pay attention to supply chain security. Due to its "zero markup" model, Cline has no built-in cost control mechanism. Although API consumption is displayed in real time, users need to set spending limits and monitor it themselves. For users who are unfamiliar with API pricing, they may be at risk of unexpectedly high bills. Some users suggested setting spending limits on API providers (for example, OpenAI and Anthropic both support setting monthly spending caps). Compared with out-of-the-box solutions such as Cursor, Cline's configuration process requires certain technical capabilities. Users need to understand the concept of API keys, pricing differences between different models, token calculation methods, etc. It is recommended that novice users start with free or low-priced models (such as DeepSeek, Ollama local models).
The technical team wants to have full control over AI model selection and cost; has multiple API accounts and hopes to switch testing between different models; needs MCP integration and browser automation capabilities; pursues open source and transparent solutions and does not accept vendor lock-in; development work involves complex multi-file reconstruction tasks. Relies heavily on inline auto-completion; prefers a smooth out-of-the-box experience; is unwilling to manage API keys and costs; needs an All-in-One closed solution. If Cline is not suitable, you can consider: Cursor (pursuing the best IDE experience, not minding closed source and subscription fees), Claude Code (heavy end users, pursuing CLI efficiency), Windsurf (similar positioning to Cursor), Continue.dev (requiring configuration flexibility), Aider (heavy terminal users).
With its core positioning of "open source, AI programming assistant", Cline occupies a unique position in the highly competitive AI programming tool market. Its 5 million+ installs, 60,500+ GitHub stars, and continuously active community prove its appeal to a group of developers with complete control and cost-consciousness. The supply chain security incident in February 2026 exposed risks, but also demonstrated community response capabilities. For developers who pursue model freedom, cost transparency, and open source controllability, Cline is still one of the most worthy of consideration. With the popularity of the MCP protocol and the continued expansion of the community ecosystem, Cline's development prospects are worth looking forward to.

User Reviews

Alan.Powell_Max98

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Cline’s Plan/Act dual mode is really easy to use. Let it come up with a plan first, confirm that there are no problems, and then execute it to avoid AI messing around.

MatthewBaker_Plus

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After using Cline for three months, my biggest feeling is that it is "controllable". Every time you change a file and run a command, you have to confirm it, unlike some tools that silently change the code. Full of security.

Kelly.MillerIII03

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I can’t go back, now I can’t open Cline when writing code and I always feel like something is missing.

Evelyn846

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It’s so powerful, Cline really changed my development process.

Donald_Thomas_2020

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Cline connects to local Ollama to run Qwen3-Coder, and the code does not leave the local machine with zero API fee. Although the response is slower than the cloud model, it is completely sufficient for daily CRUD and simple function development. For the team, data security is directly full.

TigerTradeWatson

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Anyone who says Cline is completely free would be lying to themselves. The tools are free, but you can easily spend $100 a month on a better model. Free is freedom, not beer. So don’t let the word “free” fool you. The actual cost depends on the model you choose and the amount you use.

ZKsyncZenAllen_btc

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Cline’s Plan mode is perfect for teams. Every change is recorded, so if there is a problem, you will know who made the change and what was changed. Audit trail artifact.

heavytiger925

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The infinite loop bug in Cline is really frustrating to fix. After fixing a lint error, it introduced another new one. After pulling it back and forth more than a dozen times, I finally changed it manually. When encountering complex problems, it is easy to get into trouble. This experience is really not good, and I hope it can be improved.

JackLong1682

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Yesterday, Cline helped me reconstruct a legacy Flask project. Views.py, which has more than 2,000 lines, was split into modules and more than a dozen files were changed. I reviewed and confirmed every step. The result passed the test in one go without even a single regression bug. Cursor cannot provide this kind of experience, because only Cline’s review mechanism allows me to safely allow it to undergo large-scale reconstruction.

GarrettJohnson_r

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Cline + Alibaba Cloud Coding Plan, the monthly fee is equivalent to RMB 360, 8 models can be used at will, which is enough for daily coding. The key is that Alibaba Cloud's direct connection speed in the country is very fast, so there is no need to bother with the network. It is much more cost-effective than buying Cursor Pro and is recommended to all domestic developers.

silvergorilla537

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Cline’s browser automation is a really underrated feature. After the front-end is modified, just let it open the page and click a few times to verify the effect, saving you the need to switch windows and refresh manually. Cursor and Copilot do not have this capability for the time being, and it is one of Cline’s exclusive advantages.

3_p2j4ia

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Yesterday I used Cline to write a unit test for the React component library, and the coverage rate went from 30% to 85%. It is really stable in writing tests, more than three times faster than my handwriting, and it thinks about boundary situations more thoroughly than me. From now on, you can safely leave the task of writing tests to it.

Heather.Peterson369997

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Cline API fees are really opaque. The token counter is running there, but I have no idea how much it will cost in conversion. Sometimes it hurts to see that it cost 8 dollars to complete a complex task. Can you add real-time expense display and budget reminder functions?

BitShark586

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In fact, using Cline and Copilot together is the best way. Copilot handles daily completion and simple editing, while Cline handles multi-step tasks and reconstruction. The two complement each other perfectly. Each one has its shortcomings when used alone, but the combination is the strongest AI configuration of VS Code.

Dorothy_Rogers_66

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The biggest barrier to Cline is not money, but configuration. MCP server, API Key, automatic approval rules, model routing - it took me an entire afternoon just to figure out these things. Not suitable for those who don't want to mess around, but it does smell good once it's mixed together.

KCookJr

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After trying a bunch of AI programming tools, I finally stayed with Cline. Not because it's the most useful, but because it's the most free. If you want to change the model, you can change it. If you want to connect it locally, you can connect it locally. You can completely control the data flow direction. In 2026, when manufacturers are locked in, this kind of freedom is too precious.

xpv93617c

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When Cline handles large projects, he will mess around as soon as the context window is full, forgetting everything he said before. New sessions must be opened frequently, and the continuity is too poor.

LaurenMartin_Max

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Cline helped me change the database migration script before. It changed 6 files and ran a bunch of SQL migration commands. There were no errors in the whole process. It would take at least a morning to write this by hand. AI programming has become an inseparable part of my daily workflow, and there is no turning back.

Log_an659

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Use DeepSeek V4 to run Cline, which is very fast and costs less than $10 per month. Unbeatable value for money for independent developers.

Brandon_Gonzales

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Cline's ability to copy assignments is indeed strong, but he is timid when it comes to writing something with business logic. Last week, I was asked to write a scheduling algorithm. After two days of fussing about it, I made all the mistakes. In the end, I finished it by myself in half an hour. AI programming is still not mature enough when dealing with complex business logic, and there is still a long way to go.

Karen.Martin_72

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There are already more than 400 plug-ins in Cline's MCP Marketplace, which can connect to databases, APIs, and cloud services. The closed-ecosystem Copilot is simply incomparable. This open ecosystem is the future and will not be locked by any one manufacturer.

Judith43_fi

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Cline changed a file and clicked the key points seven or eight times for confirmation, and the rhythm was completely interrupted. Can a smart mode be added to automatically allow low-risk operations?

Jessica_Rodriguez_Pro

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Beginners should use Cline with caution. Without programming foundation, one cannot judge whether the code generated by AI is right or wrong. AI programming is an amplifier, not a crutch.

小鱼873

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.clinerules is so useful. Write a rules file in the project root directory, and the coding style, architectural conventions, and testing requirements will all be automatically followed. When a new member of the team comes, there is no need to review the code specifications repeatedly. Cline automatically follows the rules, which saves a lot of worry.

RBrownJr695

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Cline's multi-file reconstruction performance is amazing, but single-file editing is cumbersome. It is more suitable for heavy work, and I still use Copilot for small changes.

Jennifer_GreenSr

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I tried it with Cline connected to GPT-5.5-Codex, and the effect was really good. But Cline has to read the entire project file every time before starting. The startup of large projects is extremely slow. After it is analyzed, I want to write it myself. I hope the logic of incremental reading can be optimized.

KyleHowardSr

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The Cline team was acquired by OpenAI? I was quite worried when I saw this news recently. Although it is officially said that the Apache 2.0 protocol will not be withdrawn, no one can say whether the direction of the community will change. Both Kilo Code and Roo Code have begun to compete for users, and the competition is fierce.

CRda_v

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Cline+JetBrains is finally here! I was stuck in VS Code before, but now PyCharm can connect seamlessly. Big bonus for heavy JB users.

剑客643

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Cline is the most stable on the road of engineering. Not the fastest, not the cheapest, but definitely the one that gives you the most sound sleep.

PaulScott_2023

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The multi-agent parallel execution function of Cline CLI 2.0 is a bit interesting. Code review and testing tasks for multiple branches can be run at the same time, and the degree of automation in the CI process has been raised to a new level. However, the configuration is much more complicated than that of a single Agent, and the documentation needs to be improved.

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