Cline

Cline, founded by Saoud Rizwan, builds an open-source AI coding agent that reads and edits files, runs terminal commands and connects to external tools. Its defining choices include separating planning from execution, letting developers choose their model providers, and exposing the agent’s work for human approval. In 2026, Cline moved its flagship VS Code extension onto a shared SDK runtime and introduced an early Desktop app for managing parallel and recurring tasks.[3][1][9][10]

The shared runtime grew out of an earlier product built around Claude 3.5 Sonnet in 2024. In his January 2026 account, Rizwan recalled spending a week in his mother’s garage in Terre Haute in July 2024 building an Anthropic hackathon demo. The idea was to give a model familiar developer tools: file access, terminal commands and codebase navigation. The demo did not win. In the July 2025 interview, he had tentatively placed the hackathon in June 2024.[6][1][9]

Cline took the form of a VS Code extension, compatible with Cursor and Windsurf as well as VS Code. Rizwan explained that this reduced onboarding friction while providing marketplace distribution, local file and terminal access, and the editor’s diff views. Nik Pash described avoiding an editor fork as a way to keep the team focused on the agent loop and support for new model families rather than maintaining the editor itself.[1]

Plan and Act formalized a workflow users had developed themselves. According to Rizwan, users were asking Cline to write Markdown architecture plans before making changes; those practices and Discord conversations informed the interface. Plan mode directs the agent to explore files, gather context and ask questions. Switching to Act directs it to execute the plan through commands and file edits. Users can supervise individual steps or enable automatic approval.[1]

The team favored agentic repository exploration: inspecting folders, following imports and reading relevant files in full. A directory-level tool exposes class and function names so the agent can decide where to look more closely. For longer tasks, the team experimented with removing duplicate file reads and replacing accumulated conversation with summaries. Pash argued that this approach worked better for coding than retrieving isolated snippets through retrieval-augmented generation; he and Rizwan also favored direct frontier-model edits over handing changes to a separate fast-apply model.[1]

In the July 2025 interview, Pash reported an internal Claude Sonnet 4 diff-edit failure rate of about 4%. He qualified the broader preference for simplicity: retrieval could still be useful for large collections of human-readable documents, and fast-apply models could help when an organization required a smaller model that struggled with search-and-replace edits.[1]

Memory Bank supplied a way to retain project context across sessions. Pash credited marketing colleague Nick Bauman with an earlier rules-based scratchpad concept; Rizwan later credited the community with building and validating Memory Bank. Pash also described a promising internal experiment in which a to-do-list tool periodically reintroduced its latest state, helping the agent stay on task through repeated summarization and context compaction.[1][6]

Cline extended its tools through the Model Context Protocol (MCP). Pash said its MCP marketplace launched in February 2025, allowing users to discover servers and have Cline install them from linked repositories. By the July interview, he reported more than 150 listed servers. He also described forking some servers to lock their versions, addressing the risk that an upstream maintainer could change code after it had been reviewed.[1]

Connected tools broadened the agent’s uses. Rizwan described Nick Bauman using Reddit and X MCP servers to scrape content and post tweets. Pash recalled building an Amsterdam conference presentation from a document of style rules and voice notes transcribed by Limitless. His own pull-request workflow combined the GitHub command-line tool, surrounding code context, a request for approval and a Slack MCP message to the team.[1]

In July 2025, Cline’s speakers described a bring-your-own-API-key approach, including direct connections to OpenAI, Anthropic and Bedrock; OpenRouter was another option. They argued that avoiding inference-margin incentives let them prioritize agent capability over reducing model costs. Rizwan summarized the position in the funding announcement: “Our thesis is simple: inference cannot be the business strategy”.[1][3]

Enterprise interest preceded a finished enterprise product. Pash recalled publishing a contact form and receiving inquiries from large organizations, including an unnamed Fortune five company with hundreds of engineers using Cline. Its concerns were which API keys those engineers used, how much they spent and where they sent data. Those requests helped shape the governance, administration and billing offering.[1]

On July 31, 2025, Cline announced $32 million in total seed and Series A funding, with the latest Series A led by Emergence Capital. Participants included Pace Capital, 1984 Ventures, Essence VC and Cox Exponential, alongside developer-focused angels. CB Insights reports the Series A itself as $27 million. The announcement also launched Cline Teams, with organization management, SSO and role-based access controls, centralized billing, spending controls and usage logs.[3][4]

Juan Pablo Flores’s February 13, 2026 account of CLI 2.0 described bringing the same agent loop into an interactive terminal interface, with Plan and Act controls and isolated conversation, state and model configuration for each instance. He illustrated the workflow with three tmux panes handling database refactoring, API documentation and migration scripts. Headless mode supported piped input and output, JSON output enabled programmatic integration, and Agent Client Protocol support connected Cline to compatible editors.[7]

The June 29 ClinePass announcement added a subscription pairing Cline’s harness with curated open-weight models. The article, updated July 16, listed $9.99 per month and advertised two to five times standard API rate limits. ClinePass appeared as a separate provider across CLI, VS Code, JetBrains and SDK, alongside users’ own keys, local models and other providers.[8]

Cline rebuilt its agent harness as a shared, modular SDK runtime, but migrating the original extension proved difficult. In his September 2 engineering account, Rizwan described replacing an approximately 76,000-line monolithic core. The first attempt took months and broke badly enough on release to require an immediate rollback.[9]

The subsequent rollout bundled legacy and SDK-based engines in one extension release. A loader selected the engine on window launch using cached state and a PostHog percentage flag. Activation failure triggered a fallback to legacy, while both engines shared settings, credentials and task storage. Flag changes took effect on a later window launch, preventing an engine switch during a task; build checks enforced compatible views and settings schemas.[9]

Cline reported that, during a full day of production traffic with cohorts near a 50/50 split, tasks reaching its three-consecutive-mistake threshold fell from 6.34% on the old harness to 0.62% on the SDK harness. This measured the point at which Cline stopped to ask for human guidance, rather than overall task success. The rollout flag reached 100% on August 23, while remaining legacy sessions continued to drain as installations updated and windows reloaded.[9]

On September 14, 2026, Cline introduced an early Desktop app with Mac and Windows downloads labeled beta. It brought the shared harness into a workspace for parallel sessions, cron-scheduled tasks and provider selection. Users could import conversations from Claude Code or Codex and continue them in Cline, or install plugins, MCP servers and skills through its marketplace.[10]

Cline’s reported installation figures grew with differing stated coverage: its July 2025 announcement claimed installations by 2.7 million developers; Rizwan’s January 2026 account reported more than five million installations across editors; and his September 2026 migration account described the VS Code extension as installed by over 11 million developers. These are company-reported installation claims, rather than active-user or paying-customer totals. The July announcement also reported use at Samsung and SAP.[3][6][9]

Pash reported a 20-person team in July 2025. By January 2026, Rizwan reported more than 35 people, many of whom had begun as open-source contributors. He credited Amazon contributors with Jupyter notebook compatibility and described Cline’s feedback and edge-case testing for Vercel AI Gateway. That month, Cline committed $1 million in Cline credits to open-source projects, with proposed awards of $1,000–$10,000 in credits; the announcement described a commitment, not cash already disbursed.[1][6]