Frequently Asked Questions

Why choose

Here are top differences between and some similar websites:

  1. uses the best converters on the market to convert files online. The best converters could be open-source projects, proprietary software or exclusive programs written by ourselves.
  2. will automatically re-submit your form to another platform/server when conversion is failed on one platform/server. This significantly increases conversion success rate.
  3. provides some exclusive online services such as identifying file format by analyzing file binary signatures or using intermediate formats for unsupported conversions.
  4. supports batch conversion mode. You can convert a bunch of files with only a few clicks, just like using a desktop converter software on Windows.
  5. is 100% free to use while some other websites may require your email address, allow choosing 2 files at max or restrict your file size to a low value unless you pay for "PRO" service.


Is it safe to convert files on

Yes, it's safe to convert files on All your files are treated as strictly confidential.

We have enabled HTTPS (Hypertext Transfer Protocol Secure) on all our servers. All file transmissions are through HTTPS instead of HTTP. HTTPS is an internet communication protocol that protects the integrity and confidentiality of data between your web browser and the site.

Your file's filename will be renamed to random 10 characters so only you can find it. Your files are only temporarily stored on our servers for 1-2 hours, after that they will be automatically deleted by a scheduled program. You can also delete all your files by yourself anytime.


What's the maximum file size and maximum execution time does support?

Different categories support different maximum file size and maximum execution time.

Category Max_file_size Max_URL_size Max_execution_time Exception
Document 40M 40M 5 minutes File with unrecognized extension name: 1M.
Ebook 40M 40M 6 minutes CHM file: 2M.
Image 200M 40M 3 minutes DWG file: 2M.
Video 200M 40M 10 minutes Video merger or video extractor: 1G.
Audio 200M 40M 10 minutes No exception.
Archive 40M 40M 5 minutes No exception.


Why has my online file conversion failed?

Here are the top reasons that may cause online file conversion failure:

  1. The server may be down or busy at the moment. It doesn't have enough CPU or memory resources to complete conversion. Tips: our servers are idle on weekends and holidays.
  2. The source format is not supported. For example, many users tried to convert WLMP file which is a movie project file that doesn't support.
  3. The source file may be corrupt, DRM protected or have a wrong file extension name.
  4. The source file may be too big or too complicated to be converted in time. We restrict some conversions to 180 seconds. The conversion will be terminated when time is up.


How can I run a conversion that doesn't support, for example: XLS to DOC?

Some unpopular conversions that are not listed on are actually supported. For example: converting audio file or image file to video file. You can directly run these conversions without problem.

Some conversions that doesn't support can use intermediate files to do. Use XLS to DOC as example: You can convert XLS file to PDF or XPS as intermediate file first, then convert the PDF or XPS file to DOC file. Using intermediate files may not have great results as direct conversion but can get the job done.

You can search for conversions at format search page. Just select a source file format, a target file format, and click the "Search" button to start searching. It will list all possible conversions that use intermediate files.


Can I directly use the converted file online without downloading it, for example: set password to a PDF file just converted?

Yes, you can reuse the file just converted. Here are steps to set a password to a PDF file just converted.

1) Right click on the output PDF file, and click "Copy link address" to copy the file link address to clipboard. The link address is directly linked to the actual online file without rewriting.
2) On the "Lock PDF" page, click on the "URL" button to switch source file from local file to online file.
3) Press "Ctrl+V" to paste the file link address copied in step 1 in the input box, set a password and click the submit button. The processing will be very quick since no file downloading or uploading.


The file conversion progress starts at 0% again when it reaches 100%. Why?

The file conversion will automatically retry another platform/server when it's failed, so you don't need to click the submit button again.

The top reason that causes online conversion failure is the server is down or busy. Therefore will automatically re-submit your form to another platform/server when conversion is failed. For example: It will try converting your file on Windows server NO.4 if it fails to convert your file on Linux server No.3.

We have deployed multiple Windows and Linux servers to increase conversion success rate. Please be patient while converting.


It supports DOCX to PDF conversion in "PDF", "Document" and "Ebook" categories. Which category should I choose?

Different categories use different conversion algorithms. DOCX to PDF conversion in the "PDF" category uses a specific algorithm while conversions in the other categories use universal algorithms.

The conversion in the "Ebook" category is designed as a pipeline. The input format is first converted to XHTML by the appropriate input plugin. This XHTML is then transformed. In the last step, the processed XHTML is converted to the specified output format by the appropriate output plugin. Using a pipeline is necessary to support vast formats with minimal source codes, however the results of the conversion can vary greatly. Some formats convert much better than others.

Compared to conversion in the "Ebook" category, conversion in the "PDF" category is designed as a direct transaction. All source DOCX file elements such as text, image, table, bookmark will be directly converted to target PDF file elements on the fly without any middle file created. It works fast and may have better results.


Why can't the output files be opened on my Windows system?

Windows systems may take security actions to protect your computer against files which are downloaded online through web browsers. This may cause these files can't be opened correctly. For example: some versions of Microsoft Office software will show error messages when opening Word, Excel or PowerPoint files downloaded online. You can unblock these files by following these steps:

Right click on file and choose "Properties" then when the properties dialog comes up, on the "General" tab, at the bottom is a "Unblock" button or checkbox next to text "Security: This file came from another computer and might be blocked to help protect this computer.", click it. If the file still can't be opened after unblocking, you can analyze the file's binary signatures to check whether it's a valid file.


Why does support so many file formats?

One of the best things about online conversions is that we can install as many programs, codecs, fonts, plugins and extensions as possible.

Since we started to develop shareware in 2000, we have tried hard to reduce shareware setup file size. Smaller setup file size can reduce bandwidth usage and make downloading faster. However we don't have file size problems anymore on online programs. We can't fill 1TB server storage up no matter how many programs we try to install. We have installed a third-party program whose file size is more than 100mb just to support one SID format.

Some file formats can only be opened on the Linux platform and some file formats can only be opened on the Windows platform. Therefore we deployed both Linux and Windows servers for this situation. supports 261 file formats by far and will continue to support more.