ComPDF and Kernstra both put a PDF editor in your web app. Only one puts every tool in the price.
ComPDF Web SDK, formerly ComPDFKit for Web, is a broad and keenly priced SDK sold by quote: ComPDF prices its SDKs by the products, features and deployment you pick, starting at $1,300 for simple use cases. The Kernstra Web SDK starts at $149 a month for an internal or back-office app, billed monthly if you like, with every tool included at that price. This page sets the two side by side, including where ComPDF Web SDK is the better choice.
- Published on the pricing page
- Monthly billing, no minimum term
- All twenty-six tools at the $149 entry price
- Free development key, watermarked
- From $1,300 for simple use cases, says ComPDF
- Annual license, per platform, at a reseller
- View and Annotation in the reseller-listed license
- 30-day trial, no watermark
ComPDF pricing next to Kernstra: what a team pays in year one.
Kernstra's entry plan, twelve months at the published price, next to the only ComPDF figures in public. The numbers are close; the difference is what each one buys. The bars share one scale.
Kernstra: the published entry price for an internal or back-office app, billed monthly; public-facing apps get a package priced to their use, and yearly billing includes two months free. ComPDF: the figures come from the public sources listed below; ComPDF quotes Web SDK prices, so your quote may differ. Sources
A price you can read today, or a quote for the features you pick.
For a startup or a SaaS team with a document feature on the roadmap, how the license is sold matters as much as the number on it.
| Kernstra | ComPDF Web SDK | |
|---|---|---|
| Price | From $149 a month for an internal app, published | Quoted; "starting at $1,300" for simple use cases; a reseller lists $1,440 a year (13 November 2026) |
| Billing | Monthly, quarterly or yearly (two months free) | Annual license, per platform, as a reseller lists it |
| Minimum term | None on monthly billing | One year, as a reseller lists it; ComPDF's own pages state no term |
| What you license | The whole SDK: twenty-six tools and the full API at the $149 entry price | A feature set: the reseller-listed license covers View and Annotation; editing, forms, signatures and more are quoted |
| What sets the price | Who uses the app, how many people, and how many apps | Products, features and deployment options |
| Domains | The domains in the license, with their subdomains when you ask; a free staging key for up to five hosts | One root domain and its subdomains per license |
| Before you pay | Development key: free, watermarked, never expires | 30-day trial key, no watermark, for testing in production |
| Time to a price | The entry price on the page; a package for your use within one business day | Contact sales with your requirements for a tailored quote |
ComPDF vs Kernstra, feature by feature, including the rows we lose.
ComPDF builds PDF software for web, server and mobile, and its Web SDK covers more ground, especially with its server products behind it. If a row marked for ComPDF Web SDK is a requirement, that should decide it.
| Kernstra | ComPDF Web SDK | |
|---|---|---|
| Viewing and editing | ||
| Renders in the browser, no server needed | Always | WebAssembly standalone mode |
| Edit existing text in the document's own font | Included at the $149 entry price | Content Editor, priced by feature |
| Large files open before the download finishes | Page streaming: a 107 MB file opens after about 0.2 MB | Not documented by ComPDF; its 3.0.0 notes say large documents open faster |
| Compare two versions of a PDF | Overlay and content compare, priced by feature | |
| React, Vue, Angular, Svelte, Next.js, Nuxt, SvelteKit | ||
| Annotation, forms and signing | ||
| Highlights, notes, drawing, shapes, stamps | Included at the entry price | In the reseller-listed license |
| Comments with threaded replies and review status | Comments panel | Replies and status |
| Real-time collaboration | Described for server-backed mode | |
| Fill existing PDF forms | Included at the entry price | Forms, priced by feature |
| Create form fields | Coming next | Forms, priced by feature |
| Drawn, typed or uploaded signatures | Included at the entry price | Signatures, priced by feature |
| Certificate-based digital signatures (PKI) | Lists declared ones; does not create or verify them | PFX and P12 certificates, priced by feature |
| Salesforce, SharePoint and Teams integrations | Salesforce guides and a SharePoint page; Teams through sales | |
| Security and processing | ||
| Documents never sent to the vendor | Nothing from the document leaves the browser | In standalone or self-hosted mode |
| Password protection and permissions | Included at the entry price | Priced by feature |
| True redaction (content removed from the file) | Black-out covers, it does not remove | Permanent redaction, priced by feature |
| OCR for scanned pages | Server side, from ComPDF | |
| Convert to and from Office formats | Server side, from ComPDF | |
| SOC 2 report | Not yet | None published |
The ComPDF Web SDK column comes from the public sources listed below: ComPDF's product pages, Web SDK guides, release notes and pricing page. "Priced by feature" means outside the reseller-listed View and Annotation license, so it is priced into the quote. Sources
When Kernstra is the better ComPDF alternative, and when it is not.
Choose Kernstra if
- You want to ship before you sign a contract. Build on a free key, go live on a monthly plan, and stop any month.
- You want every tool without pricing each one. Text editing, form filling, signatures and passwords come with the $149 entry plan.
- Your app lives on more than one domain. A license covers the domains you need, with their subdomains when you ask, and a free staging key covers up to five staging hosts.
- Documents must never leave the browser, with nothing for you to host and no upload step to add to a data-processing review.
Choose ComPDF Web SDK if
- You need certificate-based digital signatures with PFX or P12 certificates, or true redaction for regulated disclosure.
- You process scans or Office files and want OCR and conversion on a server you host, from the same vendor.
- You compare document versions or build forms in the browser today, or embed PDFs in Salesforce, SharePoint or Teams.
- You qualify for its Community License as an individual, a start-up, a non-profit or a team of five or fewer: ComPDF prices it below its normal licenses.
Switching from ComPDF to Kernstra.
Both SDKs mount into one element and take a document and a configuration object, so the shape of your code stays the same.
- 1Take a free development keyRun Kernstra beside your current viewer on localhost or any HTTPS host while you compare. The key is watermarked and never expires, so there is no trial clock.
- 2Swap the mount call
Kernstra.init({ license })andnew PDFViewer(container, doc, config)replaceComPDFKitViewer.init(); the container and the document URL carry over, and your toolbar choices map ontotoolbarandtools. - 3Map your eventsPage, form-field, signature and export events have counterparts in the SDK API reference.
- 4Go live monthlyMove to a production key when you are ready. Your ComPDF license year can run out while you are already live.
Questions before you switch from ComPDF or sign.
Anything else, ask in the quote form and an engineer answers in writing.
Ask in the quote formIs ComPDF the same as ComPDFKit?
Yes. ComPDFKit is now ComPDF, made by PDF Technologies, a KDAN company. The Web SDK is the product formerly called ComPDFKit for Web; its npm package and viewer are still named ComPDFKit.
How much does ComPDF Web SDK cost, and where do these prices come from?
From public pages, listed in the sources below. ComPDF's pricing page says pricing depends on products, features and deployment options, "starting at $1,300" for simple use cases, and its buyer's guide gives "as low as $1,300" as the first-year cost. The $1,440 figure is the reseller ComponentSource's list price for a one-year license per platform with View and Annotation, as read on 13 November 2026. That license does not name text editing: ComPDF lists its Content Editor as a separate feature, and other features are quoted. If a figure is wrong or out of date, tell us and we will correct it.
Is $149 really the price, or a teaser?
It is the published price of the entry plan: an internal or back-office app with a limited number of users, every tool included, Edit Text and Add Text among them. A public-facing app, or larger use, gets a package priced to its use within one business day, never below $149. Billing is monthly with no minimum term, quarterly, or yearly with two months free.
Does Kernstra do everything ComPDF Web SDK does?
No. Certificate-based signing, true redaction, OCR, Office conversion, document compare, real-time collaboration and the Salesforce, SharePoint and Teams integrations are in ComPDF Web SDK's offering, not in Kernstra today. Measurement and form field creation are in ComPDF Web SDK now and coming next in Kernstra.
Can we try both side by side?
Yes. ComPDF gives a 30-day trial key without a watermark; a Kernstra development key is free, watermarked and never expires, so you can run both on the same page of your app and decide on your own schedule.
Build it this afternoon. Decide about a plan when there is something to ship.
A free development key, the whole SDK, and a published price you can check without a call.
Sources, checked 27 October 2026; reseller price read 13 November 2026
ComPDF and ComPDFKit are trademarks of their owner. Every figure and claim about ComPDF on this page comes from the public sources listed here, read on 27 October 2026. If anything is wrong or out of date, tell us at hello@kernstra.com and we will correct it.
- ComPDF Pricing
Pricing depends on products, features and deployment options; "pricing for simple use cases starting at $1,300". A free 30-day deployment trial key for all platforms, to test in production without watermarks, unlimited files and users. No list prices, term or reply time stated.
- PDF SDK Buyer's Guide 2026
ComPDF SDK first-year development cost "as low as $1,300".
- ComPDF Prices (ComponentSource)
1 User Annual 1 Year license, one license per platform, per year, View and Annotation, $1,440; renewed each year. Read on 13 November 2026.
- ComPDF SDK for Web
Standalone WebAssembly mode renders without a server and keeps data on the client; self-hosted or cloud-hosted server-backed mode, described as letting users "collaborate in real-time"; Salesforce, SharePoint, OneDrive and Teams integrations (the last two through sales); conversion and compare features.
- ComPDF Web PDF SDK Overview
Content editing; form fields created and filled; electronic and digital signatures; redaction; measurement; overlay and content comparison; passwords; guides for Vue, React, Angular, Next.js, Nuxt, Svelte, SvelteKit and plain JavaScript.
- Digital signatures — Web
Full support for PFX and P12 certificates; create and verify digital signatures.
- Release Notes of PDF SDK for Web
Annotation replies and status (v2.3.1); digital signatures (v2.4.0); redaction that permanently removes content (v2.5.0); measurement (v2.7.0, v2.7.1).
- Best Web PDF SDK for Developers: Browser vs. Server-Backed Comparison
Browser-side SDKs run in the browser via WebAssembly; a server-backed Docker component handles conversion, OCR, batch compression and large-file operations.
- ComPDF SDK
PDF conversion with "AI OCR for scanned files", redaction, digital signatures and document comparison across the SDK line; a 30-day full-feature trial.
- compdfkit-web-example-vanilla-javascript (README)
Each license is valid only for a root domain and its subdomains; npm package @compdfkit_pdf_sdk/webviewer, mounted with ComPDFKitViewer.init().
- Community License for Individuals and Enterprises
For individual developers, teams of five or fewer, start-ups and non-profits; unlimited deployments; redistribution or OEM use agreed case by case.
- Security Policy
Encryption in transit and at rest; the certifications it names are its cloud host's; no SOC 2 report published.
- A Showcase of ComPDF's Website and Logo Rebranding
ComPDF is made by PDF Technologies, Inc., a KDAN company.
- ComPDF: a new service ecosystem
ComPDF is "evolving from ComPDFKit (PDF SDK & Conversion SDK) and ComIDP to ComPDF SDK, ComPDF Cloud, and ComPDF AI".
- ComPDFKit Community License for start-ups
"Compared with normal licenses, our specifically designed Community License has a lower price."