PDF gets you a page. Drawings need more than a page.
Most teams that add drawings to a web product start with a PDF SDK. For documents, that is often the right move. For technical drawings, the question is how much of the drawing survives the trip into PDF, and how much workflow your team must build on top.
PDF SDKs render pages. Rasterex puts drawings to work.
Open-source libraries such as pdf.js render PDF in the browser and leave everything above rendering to you. Commercial PDF-first SDKs provide a mature PDF toolkit and typically bring CAD in by converting it to PDF.
Rasterex starts from the drawing. DWG, DGN and IFC are read into Rasterex's own format, so layers, blocks, attributes and layouts remain available to your code. PDF, CAD and BIM open in one canvas, with compare, measure, annotate and extract as capabilities you call.
Choose a PDF SDK when your product is about documents. Choose Rasterex when your users work on technical drawings.
Three starting points. Very different amounts of product work.
| Decision point | Open-source PDF | Commercial PDF-first SDK | Rasterex |
|---|---|---|---|
| Starting point | A free PDF renderer for the browser. | A full PDF toolkit: view, edit, annotate and convert. | An embeddable canvas and SDK built for technical drawings. |
| How CAD arrives | Not supported. DWG must be converted to PDF somewhere else first. | Converted to PDF, typically through an add-on module. Layers can be kept as PDF layers. | Read into Rasterex's own format. Layers, blocks, attributes and layouts stay available to your code. |
| BIM and IFC | Outside scope. | Outside the PDF model. Check the specific product. | IFC in the same canvas and API as PDF and DWG. |
| Drawing workflows | Basic annotation: free text, ink, highlight and stamp. Scale, measure and compare are yours to build. | Broad PDF annotation. Measurement and compare depend on product and licence. | Annotate, calibrated measure, revision compare, highlight, extract and export as composable capabilities. |
| Who owns fidelity and performance | Your team: dense vector sheets, fonts, edge cases and fixes. | The vendor, for the PDF. The conversion step decides what the drawing became. | Rasterex, for the drawing formats themselves. |
| Best fit | Displaying documents, with a team ready to build the rest. | Document-centric products where CAD is occasional. | Products where technical drawings are central to the work. |
This compares integration approaches, not every product in each group. Scope varies by product, version and licence.
pdf.js is a renderer. Everything above it is yours.
pdf.js renders PDF in the browser, is free and widely used. Its built-in editor covers free text, ink, highlight and stamps. For reading documents, that is often enough.
For technical drawings, your team still owns:
- Scale and calibration, so a line on screen becomes metres on site
- Length, area, perimeter and count that hold up under zoom and rotation
- Revision compare that aligns two sheets and shows what changed
- Markup stored in your database, with IDs your records can point to
- Performance on large, dense vector sheets
- Every format that is not PDF: DWG, DGN and IFC
The licence is free. The ownership is not.
When a customer's heaviest sheet renders incorrectly or slowly, your team is responsible for the fix.
Commercial PDF SDKs bring DWG in by turning it into PDF.
Commercial PDF-first SDKs can provide annotation, forms, redaction, office conversion and, depending on the product and licence, measurement. CAD support is commonly delivered by converting DWG, DXF and DGN into PDF. Layers may remain as PDF layers.
A PDF is a page description: lines, text and layers. A DWG is a model: blocks with attributes, external references, layouts, model space and objects with identity. After conversion, an equipment tag stored in a block attribute becomes text on a page. Your code can no longer ask which valve it belongs to.
- Linking a symbol on the sheet to an asset or work order
- Counting blocks for takeoff and quantities
- Reading tags to reconcile a drawing against a register
PDF-first SDKs give you the PDF. Rasterex keeps the drawing.
The value sits in the layer above the file.
Opening a drawing is the start, not the product. Rasterex supplies the work layer as capabilities called from your code, with one API across PDF, DWG, DGN and IFC.
Compare
Overlay two revisions and see what was removed, added and kept. Compare DWG revisions as well as PDF. When origins differ, align the sheets with matching points.
Measure
Length, area, perimeter and count on a calibrated scale. Every measurement comes back to your code as an event.
Annotate
Markups, comments, stamps, freehand and review threads. Use the Rasterex backend or your own database, with XFDF and JSON data.
Extract
Read blocks and attributes from a DWG, so a symbol on the sheet can link to a record in your system and navigate back to it.
Control and export
Drive tools, layers and events from code. Export flattened PDFs, markups and scaled prints.
Choose by what your users do with the drawing.
You mainly display PDFs, users read more than they work on drawings, and you have developers ready to build and maintain the tools on top.
Your product is document-centric, such as contracts, forms and office files, and CAD arrives occasionally and only needs to look right.
Technical drawings are where the work happens, DWG, DGN and IFC need to remain structured data, and time to market matters more than owning the engine.
Ask the questions behind the PDF decision.
- 01Are our users reading drawings, or working on them?
- 02Do we need the data inside the drawing, such as blocks, attributes and layers, or only the picture?
- 03Who fixes it when a customer's heaviest sheet renders wrong or slowly?
- 04Which formats will we support in two years: PDF only, or DWG, DGN and IFC too?
- 05Where should our developers create value: in a drawing engine, or in our product?
PDF gets you a page. Rasterex puts the drawing to work.
Questions teams ask before choosing a drawing SDK.
What is the best PDF SDK for technical drawings?
It depends on whether your users read drawings or work on them. For reading PDFs, an open-source renderer such as pdf.js or a commercial PDF SDK is enough. For measuring, comparing, marking up and linking drawings to your own data, you need an SDK built for technical drawings. Rasterex is built for that job and covers PDF, DWG, DGN and IFC in one canvas.
How do I work with technical drawings inside my own system?
Embed a drawing canvas in your application instead of sending users to a separate viewer. The canvas handles rendering, markup and measurement. Your system keeps the users, the data and the workflow. With Rasterex you install one npm package, call its API from your code, and store markups and measurements where your project data already lives.
Can a PDF SDK open DWG files?
Most PDF SDKs cannot open DWG directly. Some commercial PDF SDKs convert DWG, DXF and DGN into PDF through an add-on module. The result looks like the drawing, but block attributes, external references and object identity do not carry over as data. Rasterex reads DWG into its own format, so that structure stays available to your code.
How do I add a DWG viewer to a web application?
Use an embeddable SDK that renders DWG in the browser, rather than converting every file to PDF first. With Rasterex, npm install @rasterex/viewer, mount the viewer in a container, and open the file with one call. The same viewer opens PDF, DGN and IFC without a second integration.
Is pdf.js good enough for construction and engineering drawings?
pdf.js is good enough for viewing PDF drawings. It does not include scale calibration, measurement, revision compare or CAD formats, so your team builds and maintains those. That is a reasonable choice when drawings are a small part of your product, and an expensive one when they are central.
How do I add measurement and quantity takeoff to drawings in my app?
You need calibrated scale, length, area, perimeter and count tools, plus a way to read the results in your own code. Rasterex provides these as capabilities, and every measurement comes back to your application as an event you can store against an estimate, a bid line or an order.
How do I compare two drawing revisions in a web app?
Overlay the two revisions and colour what was removed, added and kept. Real revisions rarely share an origin, so you also need a way to align them. Rasterex compare works on PDF and DWG, includes point-based alignment, and returns the result as a new document.
How do I store drawing markups in my own database?
Choose an SDK that exposes markups as data, not only as marks baked into a file. Rasterex supports XFDF import and export and gives annotation data as JSON. You can use the Rasterex annotation backend or replace it with your own database.
Can I link a symbol on a drawing to a record in my system?
Yes, if the SDK can read what the symbol is. In a DWG, equipment tags usually sit in block attributes. Rasterex reads blocks and attributes, so a valve on the sheet can be linked to an asset or work order, and the record can navigate back to the exact spot on the drawing.
Which SDK opens PDF, DWG and IFC in one viewer?
Most teams end up combining a PDF SDK, a CAD SDK and a BIM viewer, each with its own API. Rasterex opens PDF, DWG, DGN, IFC, images and MS Office through one integration and one API.
Can a drawing SDK run self-hosted or offline?
Rasterex installs on your own server and supports on-premises and fully offline deployments. You can also install it on-premises for your own customers. Drawings stay on infrastructure you control.