EldoS | Feel safer!

Software components for data protection, secure storage and transfer


Instant control over file and folder operations in Windows and .NET applications

CallbackFilter lets you monitor and control disk activity, track file and directory operations (create, read, write, rename etc.), alter file data, encrypt files and much more...

CallbackFilter is a component for use in software development for Windows® platform.

Frequently Asked Questions about licensing and ordering

What does the license include?

  • the right to use and distribute the product or it's parts according to the chosen license agreement;
  • complete source code (when Company License With Source Code is selected);
  • free standard support;
  • free code updates until release of version 5 and significant discounts on next major version.

Do you offer support by e-mail? By phone?

You are welcome to read detailed explanations about e-mail support and phone support on the corresponding web pages.

What are single-developer, private business and company licenses?

Single-developer license (available only for chosen products) must be purchased for every developer that uses the product in development process. Eg. you have 5 developers, working on the client-server project. Three of them use the product. There is also a person that does Quality Assurance (testing the application). You need a license for 3 developers. Each developer who installs the product and uses this installation in his work, even if this developer doesn't use the product directly, needs a license. NOTE: single-developer licenses are fine for companies and organizations (the name "single-developer" refers to the number of developers and not to the fact, that the developer doesn't have a company)

Company license is a license that allows all developers of the company/organization, who are located in one country, to use the product. In the example above, if three developers work in the same building or campus, you can buy one company license. If one of three developers works in other country, his use of the product is not covered by the company license and you must purchase a single-developer license for him.

Note, that the Company license (except Ultimate license) does not cover the use of the product by your contractors if you outsource part of the project: if the contractor is a separate company/organization, it must purchase its own license. Alternatively you can purchase Ultimate license for the product: this type of license covers subcontractors.

Private business license (available for Callback File System, Callback Filter, CallbackDisk, SolFS and RawDisk) is a special kind of license which is offered to small privately owned companies and startups (usually under 10 people). This license allows use of our software product by one or two programmers for development, testing and deployment (according to the chosen license type). Private Business License is offered at a discounted price.

What are the differences between various license types for your products?

The products are available under several license types for various needs:

  1. Vendor
  2. In-House
  3. Ultimate
  4. Middleware

See textual description of each license.

  In-house Vendor Ultimate
One-time fee with no royalties yes yes yes
The license covers development and deployment yes yes yes
Standard support included yes yes yes
Development within one country yes yes yes
Free minor updates and upgrades for at least a year yes yes yes
Vendor and Ultimate licenses
Deployment is allowed outside of your company/organization no yes yes
Ultimate license only
The license covers subcontractors no no yes
Priority support included no no yes
Development worldwide no no yes
  In-house Vendor Ultimate


In-House license is used by companies, which need our product(s) for internal company use, such as custom in-house software or automation purposes. In-House license does not include the right to redistribute the products to other companies / organizations or individual users. In-house license offered on per-developer basis and also available as "company licenses", i.e. usable by any number of developers in one company/organization in one country. Optionally you can purchase Worldwide License licensing option, which lets you use the company license worldwide.

Vendor license is offered to Independent Software Vendors (both individuals and companies), who develop and license their end-user software, public web applications or web services to third-parties or for own use (eg. to run publicly available web application). If you develop the software, which is planned to be distributed to other companies / organizations or individual users or if you build a public web application or web service, then this license it the most likely option for you (it's possible, that you will find Middleware or Ultimate license more applicable, though). Vendor license offered on per-developer basis and also available as "company licenses", i.e. usable by any number of developers in one company/organization in one country. Optionally you can purchase Worldwide License licensing option, which lets you use the company license worldwide.

Ultimate license is offered to the companies, who want to use the products worldwide (i.e. including all subsidiary companies and branches worldwide) for any commercial or in-house purpose including but not limited to redistribution as a part of their end-user software or web applications and web services (where applicable). Ultimate license also offers priority Standard support. Ultimate license can be used by any number of developers and on any number of systems in the company/organization, as well as subsidiary companies/organizations and contractors worldwide.

Middleware license is a special kind of license which is used by Independent Software Vendors (both individuals and companies), who develop and license their software components and modules (i.e. VCL and .NET components, C++ or COM libraries, ActiveX or .NET controls etc.) to other companies / organizations or individual users which in turn act as software developers and use the mentioned software modules in their software products. Middleware license can be used by any number of developers in one company/organization in one country. Optionally you can purchase Worldwide License licensing option, which lets you use the company license worldwide. Middleware license includes a Vendor license as well.

Can I upgade the license type (from In-house or Vendor to Vendor or Ultimate)?

Yes, you can. In-house license can be upgraded to Vendor or Ultimate, and Vendor license can be upgraded to Ultimate. The license can be upgraded if the "old" license is for current version or can be upgraded to current version free of charge. If there's a paid upgrade involved, it needs to be upgraded to current version first.  

The price of such upgrade is calculated as the difference between the cost of the "new" license and the sum paid for the previous license. I.e. if you have purchased in-house license for $1000 and now you need Ultimate license for $4000, you pay $3000.  

Our lawyers would like to make changes in your license terms. Is this possible?

List prices (the ones that price calculators and price lists on our site offer) are applicable only to the regular license terms.

If you want license terms to be modified, we can discus offered modifications. If these are minor adjustments and corrections (such as clarification of certain terms) which could be included into the public license, we are likely to accept them and use them in our regular license. If you want to make substantial changes in license terms, be ready to pay custom price for the license. This price will cover both our potential risks put into the license agreement by your lawyers and the cost of legal services charged by our lawyers for analyzing your changes.

Do I have to pay when distributing your components with my product?

The license cost is one-time and no distribution fees or other runtime fees (royalties) are required.

Note, that you may distribute our components with your software outside of your company after you have purchased Vendor or Ultimate license. In-house license lets you use our components with your software for in-house purposes only i.e. to automate some internal business process or when you create software for internal use by colleagues in your company.

Is a single-developer license "named" or transferrable?

The licenses are issued to the company (if the company name specified in the order), so they are not bound to any individual name.

One thing to do is unlink the license ticket from the user record if this user leaves the company. If the user (or we) don't do this, then new user will not be able to link the license ticket to his user's record and so he won't be able to access the license information via My Control Center section of the EldoS web site.

I develop a project for my client. What kind of license do I need to buy?

If you are providing custom software development services to the client and want to include our product as part of developed solution for one client, then your service is similar to work for hire, and you can be treated as an employee of the client (in this particular situation and for licensing purpose only). Consequently you can purchase a license for our product as if the client purchased it, i.e. for client's name and according to client's further plan to distribute the created software.

If you are providing custom software development services to many clients and want to include our product as part of developed solutions for different clients, the license should be purchased for each client as described above. Also, in such scenarios you can become our reseller or purchase several licenses (for different clients) with discount. In the latter case please contact us using one of contact options.

I live in ... . How do I purchase your product?

First of all please check our regular ordering process for the chosen product. This process includes online ordering with a credit card, wire (bank) transfer, cheque or PayPal payment.

If online ordering is not suitable for you for some reason, you can use services of one of our resellers.

Do you have reseller discounts?

Yes. Please see our Partner program page for details.

Does the price include European VAT?

Prices listed in the price lists and shown by the price calculator do NOT include VAT. We do not collect VAT from European customers.

Why can't I get bug fixes for my [old] version of your product for free? I only need bug fixes, not new features.

When you purchase the initial license, certain period of free minor updates and also new version upgrades is included. So you always get updates and fixes and new features for free for at least one year.

But the life time of certain product release is not very long because of two factors:
a) there exists significant demand for timely delivery of compatibility and interoperability updates and other improvements;
b) our products are monolithic, i.e. a change in code usually requires creation of new build of software package - old version can't be patched or updated in parts.

So we release updates and upgrades (new versions) frequently. And due to mentioned factors we don't provide bug fixes for old versions. You can buy a new version with discount and get a new round of free updates and upgrades. That will be a purchase of the new version, which includes bug fixes.


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As of July 15, 2016 EldoS business operates as a division of /n software, inc. For more information, please read the announcement.

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