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You can deliver a PDF from a browser without installing a third-party package: turn an already-valid PDF byte sequence into a Blob, create an object URL, then preview it or offer it through a download link. Those browser APIs do not generate PDF contents, however. Writing the PDF bytes yourself is a separate, format-specific task—and one you should take on only if your requirements are tightly controlled and you can maintain compatibility.
What “zero dependency” means in a browser
Blob, URL.createObjectURL(), URL.revokeObjectURL(), and an anchor’s download attribute are browser platform features, not third-party packages. They handle packaging and delivering bytes. They do not turn ordinary text or JavaScript objects into a valid PDF.
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The central distinction is therefore between generating the PDF and delivering the generated file. The delivery step is short. A hand-built PDF writer must separately produce correct PDF contents and structure; the browser APIs below cannot verify or repair those bytes.
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Assuming pdfBytes is already a valid PDF byte sequence, use it to create a PDF Blob and an object URL:
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const blob = new Blob([pdfBytes], { type: 'application/pdf' });
const url = URL.createObjectURL(blob);
// Preview in an iframe:
iframe.src = url;
// Or offer a download:
link.href = url;
link.download = 'document.pdf';The download value suggests a filename; it does not guarantee that every browser will save the file in exactly the same way. Browser settings, prompts, and behavior can affect the result. MDN documents the Blob URL and download behavior.
Release object URLs at the right time
An object URL keeps its underlying object available while the URL is active. Revoke it with URL.revokeObjectURL(url) when the preview or download no longer needs it. Do not revoke it immediately after assigning it to an iframe or link if the user still needs to open, inspect, or save the resource.
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If a user action replaces a preview, release the old URL when it is no longer in use, then create and assign the new one. PDFKit’s browser demo illustrates this pattern: it builds a Blob from document chunks, previews it through an object URL, and revokes a previously held URL when replacing the preview. See the PDFKit browser example.
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A strict no-third-party-dependency requirement may justify a custom writer, but it transfers responsibility for PDF correctness and compatibility to your code. The documentation reviewed here does not establish a complete minimal PDF writer, so the Blob example is not a recipe for generating a PDF from scratch. If the document needs features beyond a narrow, controlled output, compare the implementation burden with a library’s documented capabilities.
| Approach | What it provides | Trade-offs to account for |
|---|---|---|
| Hand-built vanilla JavaScript | No third-party PDF package; you control the generated bytes. | You own PDF structure, formatting, and compatibility details. The browser delivery APIs do not solve those format requirements. |
| pdf-lib | Its project documentation describes browser support and creation and modification of PDFs, including pages, text, images, custom fonts, forms, and merge/split operations. save() returns a Uint8Array, which can be passed to a Blob. |
It is a dependency, so it does not meet a strict zero-third-party-dependency requirement. Embedding custom fonts requires the separate @pdf-lib/fontkit module. See pdf-lib documentation. |
| PDFKit | It supports browser use. Its browser documentation demonstrates collecting output chunks and making a Blob for preview. | The browser build cannot access the filesystem, and standard fonts need registration in the browser build. The documentation labels its toBlob and toBytes output helpers experimental; the documented chunk-collection approach avoids presenting those helpers as stable. See PDFKit browser documentation. |
Use a library’s output with the same browser delivery flow
With pdf-lib, the documented save() result is a Uint8Array, which can be wrapped in the same application/pdf Blob shown above. With PDFKit in the browser, follow its documented output pattern: collect emitted chunks, construct the Blob, and create an object URL for the preview. For both libraries, follow their setup instructions for the target browser rather than assuming Node.js filesystem behavior is available in a web page.
Quick Recap
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Decide whether a custom writer is worth maintaining
- Choose a hand-built writer only when “no third-party packages” is a real requirement, the documents are tightly constrained, and you are prepared to own format correctness and browser compatibility.
- Evaluate pdf-lib when you need browser-compatible creation or modification with documented support for features such as forms, images, custom fonts, or page operations.
- Evaluate PDFKit when its documented browser output and document-generation approach fit your needs, while accounting for its browser-specific filesystem and font setup constraints.
- Keep the delivery layer separate from PDF generation. A Blob and object URL are useful regardless of which method produced valid bytes.
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