# How to Use OfficeCLI HTML Rendering Engine for Document Previews > Learn how to use OfficeCLI's HTML rendering engine to convert DOCX, PPTX, and XLSX files into browser-ready HTML previews. Effortlessly generate document snapshots with the view command. - Repository: [OfficeAI/OfficeCLI](https://github.com/iofficeai/OfficeCLI) - Tags: how-to-guide - Published: 2026-08-06 --- **OfficeCLI's built-in HTML rendering engine converts DOCX, PPTX, and XLSX files into self-contained, browser-ready HTML snapshots via the `view` command with `html` mode.** The rendering engine produces a single HTML file with all assets inlined, making it ideal for CI artifacts, agent workflows, and quick visual validation without external dependencies. For DOCX files, the engine assembles a complete document starting with `` through the closing `` tag in [`WordHandler.HtmlPreview.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/WordHandler.HtmlPreview.cs) (lines 160‑1398). The same renderer powers the live `watch` command, ensuring identical output between one-shot previews and streaming updates. ## Activating the HTML Rendering Mode The HTML preview workflow begins in [`CommandBuilder.View.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/CommandBuilder.View.cs). When you invoke `view html`, the CLI validates the `--render` flag, instantiates a fresh `RenderOptions` object, and calls `RenderViaRegistry` to route the request to the appropriate format handler. ```bash # Basic usage – outputs absolute path to temporary HTML file officecli view report.docx html ``` The handler receives the `RenderOptions` instance and returns a fully inlined HTML document. The CLI writes this to a temporary file and prints the path to stdout for immediate browser opening or scripting. ## Supported File Types and Handlers OfficeCLI routes HTML rendering through format-specific handlers based on file extension: | Extension | Handler | Source File | |-----------|---------|-------------| | .docx | `WordHandler.HtmlPreview` | [`src/officecli/Handlers/Word/WordHandler.HtmlPreview.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/src/officecli/Handlers/Word/WordHandler.HtmlPreview.cs) | | .pptx | `PptHandler` | Referenced via `RenderViaRegistry` | | .xlsx | `ExcelHandler` | Referenced via `RenderViaRegistry` | Each handler produces identical output structure: a standalone HTML file with embedded CSS, fonts, and images. The [`ResidentServer.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/ResidentServer.cs) file reuses this same pipeline for incremental preview updates during `watch` sessions. ## Controlling Output Location and Scope The `view html` command accepts several flags to customize the generated preview: ```bash # Save to specific path instead of temporary file officecli view deck.pptx html -o /artifacts/deck-preview.html # Render specific page from Word document officecli view contract.docx html --page 3 # Limit spreadsheet preview to sheets 1-2 officecli view budget.xlsx html --start 1 --end 2 ``` In [`CommandBuilder.View.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/CommandBuilder.View.cs) (lines 143‑151), the `--page`, `--start`, and `--end` parameters populate the `RenderOptions` object before the registry dispatch. ## Integration with Live Preview and Automation The HTML engine serves dual purposes. According to [`ResidentServer.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/ResidentServer.cs), the same `RenderViaRegistry` call with fresh `RenderOptions` handles both: - **One-shot previews**: `view html` for static output - **Streaming updates**: `watch` command for live editing feedback This design guarantees that agents and CI pipelines receive visually identical results. The README confirms that output is "standalone HTML file, assets inlined. Open in any browser." The SKILL guide recommends `view html` for automated QA pipelines and visual regression testing. ## File Structure and Implementation Details Understanding the source layout helps when extending or debugging the renderer: - **[`src/officecli/CommandBuilder.View.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/src/officecli/CommandBuilder.View.cs)**: Entry point, argument parsing, `RenderOptions` construction - **[`src/officecli/ResidentServer.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/src/officecli/ResidentServer.cs)**: Orchestrates `watch` mode with same HTML pipeline - **[`src/officecli/Handlers/Word/WordHandler.HtmlPreview.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/src/officecli/Handlers/Word/WordHandler.HtmlPreview.cs)**: DOCX-specific HTML generation with full document structure The [`WordHandler.HtmlPreview.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/WordHandler.HtmlPreview.cs) implementation demonstrates the engine's thoroughness: it constructs valid HTML5 from DOCTYPE declaration through final closing tag, handling complex document elements including tables, footnotes, and embedded media. ## Summary - **Primary command**: `officecli view html` triggers the rendering engine - **Output**: Self-contained HTML with inlined assets, written to temp file or specified path - **Implementation**: [`CommandBuilder.View.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/CommandBuilder.View.cs) builds `RenderOptions`, `RenderViaRegistry` dispatches to format handlers - **Consistency**: Same engine powers `view` and `watch` commands - **Customization**: `--page`, `--start`, `--end`, and `-o` flags control scope and destination ## Frequently Asked Questions ### Can I use the HTML renderer without installing a browser? Yes. The engine generates standard HTML5; any environment can save, archive, or serve the output. The file prints to stdout as an absolute path for headless workflows. ### Does the HTML output require internet access to render? No. According to the source implementation in [`WordHandler.HtmlPreview.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/WordHandler.HtmlPreview.cs), all CSS, fonts, and images are base64-inlined. The resulting file opens correctly in air-gapped environments. ### How does `view html` differ from `watch` mode? The `view` command produces a single snapshot and exits. The `watch` command uses [`ResidentServer.cs`](https://github.com/iOfficeAI/OfficeCLI/blob/main/ResidentServer.cs) to call the identical renderer repeatedly on file changes, streaming updated HTML paths to connected clients. ### Which Office formats support page and sheet limiting? The `--page` flag applies to DOCX files. The `--start` and `--end` flags apply to XLSX files for sheet range selection. PPTX files currently render complete decks; per-slide selection requires post-processing the output.