Dylibso
7 known investors
Dylibso builds developer tooling and infrastructure that helps engineering teams run WebAssembly in production.
Also known as Dylibso, Inc.
Investors · 7
Also in the syndicate · 6
Company profile
researched Aug 2026Dylibso is a software company that develops tools and infrastructure for taking WebAssembly (Wasm) to production. Its two initially released products are Extism, an open-source universal plug-in system that allows developers to embed WebAssembly-compiled code into existing programs written in other languages, and Modsurfer, a system of record and diagnostics application for WebAssembly binaries. Extism is described as not a commercial product but as a project intended to accelerate WebAssembly adoption, particularly outside the browser; it provides SDKs for host languages (reported as 16-17 languages including Python, Rust, Go, Ruby, C++, Java, Zig, C# and PHP) and Plug-in Development Kits (PDKs) that handle low-level concerns such as passing complex data types across the Wasm boundary and orchestrating capability-based security for host access.
Modsurfer addresses observability and debugging of Wasm modules, which are opaque binaries. It analyzes modules to detect the original source language, imports and exports, namespaces, code complexity (including cyclomatic complexity analysis to characterize runtime risk), and supports searching, security scanning, compatibility validation and CI/CD pipeline integration via CLI and GitHub Actions. Modsurfer is free for developers with an enterprise version offered commercially.
Dylibso's public GitHub organization hosts roughly 79 repositories, including Chicory (a native JVM WebAssembly runtime), Hermit (a portable WebAssembly compiler toolchain for self-contained cross-platform binaries), observe-sdk (continuous runtime observability SDKs for WebAssembly), Modsurfer, wasmstore (a content-addressable datastore for Wasm modules), and a family of XTP tooling projects including bindgen templates for Go, Zig, C++ and TypeScript, test frameworks for XTP/Extism plugins, and an archived repository of official servlets for mcp.run.
Founding story
The company was founded in 2022 by co-founder and CEO Steve Manuel together with Zach Shipko and Benjamin Eckel. Manuel previously worked at Cloudflare, where he brought WebAssembly support to the Workers product, and at quantum computing company Rigetti Computing. He describes building, as a side project, a framework compiled to WebAssembly from Rust that integrated with Cloudflare's APIs, and finding he had no observability into how that code behaved in production — problems that shaped Extism and Modsurfer. Crew Capital states it was introduced to Manuel by Shomik Ghosh of Boldstart and has been an investor since day one.
Business model
Dylibso combines open-source distribution with commercial products: Extism is released as open source to drive WebAssembly adoption and is explicitly not sold, while Modsurfer is available free to individual developers with a paid enterprise version described as the company's first commercial product.
Commercial revenue is derived from an enterprise version of Modsurfer, with the base tool free to developers; Extism is open source and not sold as a product.
Traction
By late March 2023 Extism had surpassed 1,800 GitHub stars with support for 16 languages, and is described as used in production at scale, including in major projects such as GitHub. Chicory has over 1,100 GitHub stars as of mid-2026, and the organization maintains around 79 public repositories.
Latest developments
Dylibso's GitHub organization shows continued activity on Chicory, the JVM WebAssembly runtime (over 1,100 stars, commits into 2026), and on XTP tooling including bindgen templates and plug-in test frameworks. A repository of official servlets for mcp.run published by Dylibso has been archived. Company blog work has also explored WebAssembly for generative AI applications, including Chainsocket, a hackathon proof of concept that chains together Extism-based plug-ins (LLM, Tool and Agent types) configured through a file, drawing on concepts from LangChain.
▸Full profile — market position, technology, go-to-market, geography, history, risks & controversies
Market position
Dylibso is positioned as a tooling vendor in the emerging WebAssembly ecosystem, where an industry analyst quoted in coverage of its seed round argued that developer struggles with Wasm stem from a lack of tooling and that the Wasm market could rival container adoption. Investor commentary frames the company as filling a nascent tooling layer alongside Wasm usage at companies such as Shopify and Cloudflare.
Sources highlight Extism's ability to add plug-in extensibility to programs regardless of the host language, with isolation and portability and broad language SDK coverage, and Modsurfer's role as a visibility layer that analyzes otherwise opaque Wasm binaries, including source-language detection and cyclomatic complexity/risk analysis, plus CI/CD integration. The company emphasizes integrating with existing runtimes and codebases rather than requiring a custom runtime.
Technology
Core technology centers on WebAssembly: Extism provides an abstraction layer over raw Wasm runtimes (such as Wasmtime, Wasmer and V8) with host SDKs and plug-in development kits handling memory/ABI concerns, string and complex-type passing, plug-in configuration and logging, and capability-based grants for host functionality. Modsurfer performs static analysis of Wasm binaries. Other projects include Chicory, a native JVM WebAssembly runtime written in Java; Hermit, a WebAssembly compiler toolchain in C producing self-contained cross-platform binaries; observe-sdk for runtime observability; wasmstore, a content-addressable datastore for Wasm modules; and XTP schema-driven code generation (bindgen) for multiple languages.
Go-to-market
Developer-led adoption through open-source projects (Extism, Chicory and related repositories on GitHub), community-contributed language SDKs, technical blog content, and conference announcements such as Wasm I/O, with commercial monetization via an enterprise tier of Modsurfer.
Software developers and DevOps teams, including enterprises adopting WebAssembly, working across languages such as Go, Rust, Ruby, Python, PHP, Java, C# and Zig.
Geography
Headquartered in Boulder, Colorado, USA, with offices also reported in Los Angeles and New Orleans.
History
Dylibso was founded in 2022. Extism was announced/launched in December 2022. In March 2023 the company announced a $6.6 million seed round at the Wasm I/O conference in Barcelona and simultaneously made Modsurfer generally available. Later work expanded the toolchain to projects such as Chicory (JVM Wasm runtime), Hermit, observability SDKs, and XTP tooling, including servlets published for mcp.run (that repository is archived).
Risks & controversies
Reported total funding figures are inconsistent across sources ($7.0M across two rounds versus $6.6M seed versus $8.2M cumulative), and one source's $6.6M seed and a separately listed $5M March 2023 seed may describe the same event. The archived status of the mcp.run servlets repository indicates at least one project is no longer maintained.
Compiled by commissioned research from 7 cited public sources — announcements, filings, and press listed under research sources below.
Key figures
latest reportedCompany-reported or press-reported figures, each dated to when it was claimed — not independently audited.
Timeline · 3
launches, deals, and filingsSeed round led by Felicis with participation from Boldstart Ventures, Pebblebed and Crew Capital, announced at the Wasm I/O conference in Barcelona.
$6.6M source ↗
Modsurfer, a system-of-record and diagnostics tool for WebAssembly binaries and Dylibso's first commercial product, became generally available; announced at the Wasm I/O conference in Barcelona.
Dylibso launched Extism, an open source universal plug-in system that lets developers run code compiled to WebAssembly inside programs written in other languages.
Dated company events from announcements, filings, and press; legal rows summarize public dockets and regulator releases.
▸Research sources · 7
primary sources listed
- Dylibso · GitHubgithub.com · web
7 public sources were cited for this profile; the first-party ones are listed here.
Frequently asked questions
- What does Dylibso do?
- Dylibso builds developer tooling and infrastructure that helps engineering teams run WebAssembly in production.
- Who are Dylibso's investors?
- Dylibso's investors include Felicis Ventures.