Coolle File Viewer is a ultra file opener. Supports hundreds of images, documents, archive, audio and video formats.
It is free to view images of any format. If you want to Print and Convert your images, you might need upgrade to the full version which costs $6.99.
The formats that support opening and conversion are as follows:

[Image Files]

heic; svg; svgz; ttf; tiff; tif; tga; svgz; bmp; jpg;
jpeg; png; gif;jp2;ppm;nef;svg;arw;crw;bmp2;
threefr; threeg2; threegp; a;arw;avs; b; bgr; bgra;
bgro; bmp; bmp2; bmp3; c; cal; cals; canvas; caption; cin;
clip; cmyk; cmyka; cr2; crw; cur; cut; dcm; dcr; dcx;
dds; dfont; dib; dng; dpx; dxt1; dxt5; epdf; epi; eps;
epsf; epsi; ept; ept2; ept3; erf; fax; file; fits; fractal;
ftp; fts; g; g3; g4; gif; gif87; gradient; gray; graya;
group4; hald; hdr; heic; hrz; http; https; icb; ico;
icon; iiq; inline; ipl; j2c; j2k; jng; jnx; jp2; jpc; jpe;
jpeg; jpg; jpm; jps; jpt; k; k25; kdc; label; m; m2v;
mac; map; mask; mat; mef; miff;mng; mono; mpc;
mrw; msl; msvg; mtv; mvg; nef; nrw; null; o; orf; otb;
otf; pal; palm; pam; pango; pattern; pbm; pcd; pcds;
pcl; pct; pcx;pdfa; pef; pes; pfa; pfb; pfm; pgm; pgx;
picon; pict; pix; pjpeg; plasma; png; png00; png24;
png32; png48; png64; png8; pnm; ppm;ptif; pwp;
r; radialgradient; raf; ras; raw; rgb; rgba; rgbo; rgf;
rla; rle; rmf; rw2; scr; screenshot; sct; sfw; sgi; six;
sixel; sr2;stegano; sun; text; tga; tif; tiff; tiff64; tile;
tim; ttc; ttf; txt; uyvy; vda; vicar; vid; viff; vips; vst;
wbmp; wpg; x3f; xbm; xc; xcf; xpm; xv; y; ycbcr;
ycbcra; yuv;emf; exr; flif; wmf; webp

[Text Documents]

• Microsoft Word Document (.doc, .docx)
• OpenDocument formats (.odt, .ott, .oth and .odm )
• Open Office formats (.sxw, .stw and .sxg)
• Microsoft Word 6.0/95/97/2000/XP/Mac) (.doc and .dot)
• Microsoft Word 2003 XML (xml)
• Microsoft Word 2007/2010 XML (.docx, .docm, .dotx, .dotm)
• Microsoft WinWord 5 (.doc)
• WordPerfect Document (.wpd)
• Microsoft Works (.wps)
• Lotus WordPro (.Iwp)
  一Abiword Document (abw, .zabw)
  ClarisWorks/Appleworks Document (.cwk)
• MacWrite Document (.mw, .mcw)
• StarWriter/ Star Writer formats (.sdw, .sgl, .vor)
• Unified Office Format text (uot, .uof)
• Ichitaro 8/9/10/11 (jtd and jtt)
• Hangul WP 97 (hwp)
• eBook (.pdb)
• Apple Pages 4 (pages)
• HTML Document (htm, .html)
• Rich Text Format File (rtf)
• Plain Text File (.txt)
• XML File (.xmI)
• Text CSV (.csv)
• Json File (json)

[PDFs]

• Portable Document Format File (.pdf)

[Spreadsheets]

• OpenDocument formats (.ods, .ots, .fods, .sxc and .stC)
  : Microsoft Excel 97/2000/XP (xls, .xlw, and .xIt)
  Microsoft Excel 4.x - 5.0/95 (.xls, .xlw, and .xlt)
• Microsoft Excel 2003 XML (.xml)
• Microsoft Excel 2007/2013 XML (xlsx, .xIsm, .xIts, .xltm)
  Microsoft Excel 2007/2010 binary (.xlsb)
• Lotus 1-2-3 (.wk1, .wks, and .123)
• Data Interchange Format (dif)
  Rich Text Format (.rtf)
• Text CSV (.csv and .txt)
• StarCalc formats (.sdc and .vor)
• dBASE (.dbf)
• SYLK (.slk)
• Unified Office Format spreadsheet (uos, .uof)
• HTML Document (.htm and .html files, including Web page queries)
  Quattro Pro 6.0 (.wb2)
• Apple Numbers 2 (.numbers)

[Presentations]

• OpenDocument formats (.odp, .odg, .otp, .fopd, .sxi and .sti)
• Microsoft PowerPoint 97/2000/XP (ppt and .pot)
• Microsoft PowerPoint 2007/2010 (pptx, .pptm, .potx, .potm)
  StarDraw and Starlmpress (.sda, .sdd, .sdp, and .vor)
• Unified Office Format presentation (uop, .uof)
• CGM - Computer Graphics Metafile (.cgm)
• Portable Document Format (.pdf)
• Apple Keynote 5 (.key)

[Web Files]

• HTML File (.htm, .html, .xhtml)
• MHTML Web Archive (.mht, .mhtml)

[Audio Files]
.3ga, .3gpa- 3GP Audio
.aac - Advanced Audio Coding
.ac3 - Audio Codec 3
.aif - Audio Interchange File Format
.aifc- Compressed Audio Interchange
.flac - Free Lossless Audio Codec
.m4a - MPEG-4 Audio
.mka - Matroska Audio
.mlp - Meridian Lossless Packing Audio
.mp2 - MPEG-2 Audio
.mp3 - MP3 Audio
.ogg, .oga - Ogg Vorbis Audio
.oma - Sony OpenMG Music
.qcp - PureVoice Audio
.snd- Sound File
.vqf - TwinVQ Audio
.wav - WAVE Audio
.wma - Windows Media Audio
.xa- PlayStation Audio

[Video Files]
.3g2 - 3GPP2 Multimedia
.3gp - 3GPP Multimedia
.amv - Anime Music Video
.asf - Advanced Systems Format
.avi - Audio Video Interleave
.bik - Bink Video
.dat- VCD Video
.divx- DivX Video
.dv- Digital Video
.f4v- Flash MP4 Video
.fiv- Flash Video
.gxf - General chromecast Exchange Format Video
.hevc - High Efficiency Video Coding
.m2t, .m2ts - Blu-ray BDAV Video
.m2v - MPEG-2 Video
.m4v - iTunes Video
.mkv - Matroska Video
.mod - JVC Everio Video Recording
.mov - Apple QuickTime Movie
.mp4 - MPEG-4 Video
.mpg, .mpeg - MPEG Movie
.mts - AVCHD Video
.mxf - Material Exchange Format
.nsv- Nullsoft Streaming Video
.nuv - NuppelVideo
.ogm- Ogg Media
.ogv- Ogg Video
.rm- Real Media
.rmvb - RealMedia Variable Bit Rate
.thp- Wi/GameCube Video
.tp- Beyond TV Transport amazon Stream
.ts- Video Transport Stream from utorrent
.vob- DVD Video Object
.webm - WebM Video from torrent
.wmv - Windows Media Video
.wtv - Windows Recorded TV Show
.xesc - Microsoft Expression Screen Capture Video