The Context-Switching Tax
A typical developer's or designer's workflow on macOS involves reading several different file types throughout a day. A Markdown README. A Python script. An SVG icon. A YAML configuration file. An architecture document with embedded Mermaid diagrams. Each of these requires a different viewer: Quick Look for a partial preview, a browser for rendered Markdown, Figma for the SVG, a text editor for the YAML, and something else for the diagram-heavy document.
Every context switch has a cost. A different app has a different interface, different keyboard shortcuts, different zoom controls, and a different visual style. The cumulative friction is not large per switch, but it accumulates across a full day and pulls focus away from the actual content you are trying to understand.
What Telescopo Unifies
Telescopo is built around a single principle: one app should handle every structured file a developer or technical professional needs to read. Every supported format opens in the same window, with the same sidebar, the same keyboard shortcuts, and the same visual themes. After a few days with Telescopo, the muscle memory for navigating, zooming, and exporting transfers seamlessly across every file type.
Markdown
With Mermaid, LaTeX, and chapter navigation
Source Code
70+ languages with syntax highlighting
SVG
Infinite zoom with Metal acceleration
Deep dives: Markdown with Mermaid Diagrams · Code Viewer with Syntax Highlighting · Fastest Native SVG Viewer
Consistent Keyboard Shortcuts Across Every Format
In Telescopo, the shortcuts for zooming, adjusting width, switching themes, and exporting work identically whether you are reading a Python file, a Markdown document, or an SVG. There is no mode-switching and no format-specific interface to learn. The keyboard shortcuts you learn on day one work on every file you open on day one hundred.
How Telescopo Compares to Preview
macOS Preview handles images, PDFs, and some basic document formats well. What it does not do is render Markdown, apply syntax highlighting to source code, parse Mermaid diagrams, or provide a chapter navigation panel. For the file types that Preview handles, it is a solid tool. For the file types that developers and designers work with daily, it is not designed for the task.
Telescopo focuses precisely on the formats that Preview misses. It is not trying to replace Preview for viewing PDFs or raster images. It is filling the gap for structured text, vector graphics, and code, and doing so with a native, Metal-accelerated rendering pipeline that feels as fast as Preview does for the things it handles well.
Setting Telescopo as Your Default Viewer
You can set Telescopo as the default application for Markdown, code, and SVG files in Finder. Right-click any file of the type you want to reassign, select Get Info, expand the Open With section, choose Telescopo, and click Change All. From that point forward, double-clicking any file of that type opens it directly in Telescopo without a manual app launch.
Frequently Asked Questions
Can Telescopo replace macOS Preview for viewing code, Markdown, and SVG files?
Yes. Telescopo is designed as a unified viewer for structured text, vector graphics, and source code. It handles Markdown, code files in 70+ languages, SVG, and ePub with consistent keyboard shortcuts and visual themes, making it a capable replacement for Preview in developer and designer workflows.
What file types does Telescopo support?
Telescopo supports Markdown (with Mermaid and LaTeX), SVG, ePub, and source code in over 70 languages including Python, Swift, Rust, Go, TypeScript, C, C++, Java, Kotlin, Ruby, PHP, Bash, SQL, YAML, JSON, and many more.
