diff --git a/apidoc.md b/apidoc.md
index ea3266a..88b1ce8 100644
--- a/apidoc.md
+++ b/apidoc.md
@@ -1,35 +1,35 @@
 ## Legacy API
 
 ```Nim
-proc encodePNG*(input: string, colorType: PNGColorType, bitDepth, w, h: int, settings = PNGEncoder(nil)): PNG
-proc encodePNG32*(input: string, w, h: int): PNG
-proc encodePNG24*(input: string, w, h: int): PNG
+encodePNG(input: string, colorType: PNGColorType, bitDepth, w, h: int, settings = PNGEncoder(nil)): PNG
+encodePNG32(input: string, w, h: int): PNG
+encodePNG24(input: string, w, h: int): PNG
 
 when not defined(js):
-  proc savePNG*(fileName, input: string, colorType: PNGColorType, bitDepth, w, h: int): bool
-  proc savePNG32*(fileName, input: string, w, h: int): bool
-  proc savePNG24*(fileName, input: string, w, h: int): bool
+  savePNG(fileName, input: string, colorType: PNGColorType, bitDepth, w, h: int): bool
+  savePNG32(fileName, input: string, w, h: int): bool
+  savePNG24(fileName, input: string, w, h: int): bool
 
-proc prepareAPNG*(colorType: PNGColorType, bitDepth, numPlays: int, settings = PNGEncoder(nil)): PNG
-proc prepareAPNG24*(numPlays = 0): PNG
-proc prepareAPNG32*(numPlays = 0): PNG
-proc addDefaultImage*(png: PNG, input: string, width, height: int, ctl = APNGFrameControl(nil)): bool
-proc addFrame*(png: PNG, frame: string, ctl: APNGFrameControl): bool
-proc encodeAPNG*(png: PNG): string
+prepareAPNG(colorType: PNGColorType, bitDepth, numPlays: int, settings = PNGEncoder(nil)): PNG
+prepareAPNG24(numPlays = 0): PNG
+prepareAPNG32(numPlays = 0): PNG
+addDefaultImage(png: PNG, input: string, width, height: int, ctl = APNGFrameControl(nil)): bool
+addFrame(png: PNG, frame: string, ctl: APNGFrameControl): bool
+encodeAPNG(png: PNG): string
 
 when not defined(js):
-  proc saveAPNG*(png: PNG, fileName: string): bool
+  saveAPNG(png: PNG, fileName: string): bool
 
-proc decodePNG*(s: Stream, colorType: PNGColorType, bitDepth: int, settings = PNGDecoder(nil)): PNGResult
-proc decodePNG*(s: Stream, settings = PNGDecoder(nil)): PNG
+decodePNG(s: Stream, colorType: PNGColorType, bitDepth: int, settings = PNGDecoder(nil)): PNGResult
+decodePNG(s: Stream, settings = PNGDecoder(nil)): PNG
 
 when not defined(js):
-  proc loadPNG*(fileName: string, colorType: PNGColorType, bitDepth: int, settings: PNGDecoder = nil): PNGResult
-  proc loadPNG32*(fileName: string, settings = PNGDecoder(nil)): PNGResult
-  proc loadPNG24*(fileName: string, settings = PNGDecoder(nil)): PNGResult
+  loadPNG(fileName: string, colorType: PNGColorType, bitDepth: int, settings: PNGDecoder = nil): PNGResult
+  loadPNG32(fileName: string, settings = PNGDecoder(nil)): PNGResult
+  loadPNG24(fileName: string, settings = PNGDecoder(nil)): PNGResult
 
-proc decodePNG32*(input: string, settings = PNGDecoder(nil)): PNGResult
-proc decodePNG24*(input: string, settings = PNGDecoder(nil)): PNGResult
+decodePNG32(input: string, settings = PNGDecoder(nil)): PNGResult
+decodePNG24(input: string, settings = PNGDecoder(nil)): PNGResult
 ```
 
 
@@ -37,19 +37,46 @@ proc decodePNG24*(input: string, settings = PNGDecoder(nil)): PNGResult
 
 
 ```Nim
-proc decodePNG*(T: type, s: Stream, colorType: PNGColorType, bitDepth: int, settings = PNGDecoder(nil)): PNGResult[T]
-proc decodePNG*(T: type, s: Stream, settings = PNGDecoder(nil)): PNG
+# generic version accept T = `string`, `seq[uint8]`
+encodePNG(input: T, w, h: int, settings = PNGEncoder(nil)): PNG[T]
+encodePNG(input: T, colorType: PNGColorType, bitDepth, w, h: int, settings = PNGEncoder(nil)): PNG[T]
+encodePNG32(input: T, w, h: int): PNG[T]
+encodePNG24(input: T, w, h: int): PNG[T]
+writeChunks(png: PNG[T], s: Stream)
+
+type
+  PNGStatus* = Result[void, string]
+  PNGBytes*[T] = Result[T, string]
+
+prepareAPNG(T: type, colorType: PNGColorType, bitDepth, numPlays: int, settings = PNGEncoder(nil)): PNG[T]
+prepareAPNG24(T: type, numPlays = 0): PNG[T]
+prepareAPNG32(T: type, numPlays = 0): PNG[T]
+addDefaultImage(png: PNG[T], input: T, width, height: int, ctl = APNGFrameControl(nil)): bool
+addFrame(png: PNG[T], frame: T, ctl: APNGFrameControl): bool
+
+when not defined(js):
+  savePNG(fileName: string, input: T, colorType: PNGColorType, bitDepth, w, h: int): PNGStatus
+  savePNG32(fileName: string, input: T, w, h: int): PNGStatus
+  savePNG24(fileName: string, input: T, w, h: int): PNGStatus
+
+encodeAPNG(png: PNG[T]): PNGBytes[T]
+
+when not defined(js):
+  saveAPNG(png: PNG[T], fileName: string): PNGStatus
+
+decodePNG(T: type, s: Stream, colorType: PNGColorType, bitDepth: int, settings = PNGDecoder(nil)): PNGResult[T]
+decodePNG(T: type, s: Stream, settings = PNGDecoder(nil)): PNG
 
 type
   PNGRes*[T] = Result[PNGResult[T], string]
 
 when not defined(js):
-  proc loadPNG*(T: type, fileName: string, colorType: PNGColorType, bitDepth: int, settings: PNGDecoder = nil): PNGRes[T]
-  proc loadPNG32*(T: type, fileName: string, settings = PNGDecoder(nil)): PNGRes[T]
-  proc loadPNG24*(T: type, fileName: string, settings = PNGDecoder(nil)): PNGRes[T]
+  loadPNG(T: type, fileName: string, colorType: PNGColorType, bitDepth: int, settings: PNGDecoder = nil): PNGRes[T]
+  loadPNG32(T: type, fileName: string, settings = PNGDecoder(nil)): PNGRes[T]
+  loadPNG24(T: type, fileName: string, settings = PNGDecoder(nil)): PNGRes[T]
 
-proc decodePNG32*(T: type, input: T, settings = PNGDecoder(nil)): PNGRes[T]
-proc decodePNG24*(T: type, input: T, settings = PNGDecoder(nil)): PNGRes[T]
+decodePNG32(input: T, settings = PNGDecoder(nil)): PNGRes[T]
+decodePNG24(input: T, settings = PNGDecoder(nil)): PNGRes[T]
 ```
 
 ## How to use PNGRes?
diff --git a/nimPNG.nim b/nimPNG.nim
index 5a598f8..0976958 100644
--- a/nimPNG.nim
+++ b/nimPNG.nim
@@ -1871,7 +1871,7 @@ when not defined(js):
   proc loadPNG24*(T: type, fileName: string, settings = PNGDecoder(nil)): PNGRes[T] =
     loadPNG(T, fileName, LCT_RGB, 8, settings)
 
-proc decodePNG32*(T: type, input: T, settings = PNGDecoder(nil)): PNGRes[T] =
+proc decodePNG32Impl*[T](input: T, settings = PNGDecoder(nil)): PNGRes[T] =
   try:
     when T is string:
       var s = newStringStream(input)
@@ -1884,7 +1884,7 @@ proc decodePNG32*(T: type, input: T, settings = PNGDecoder(nil)): PNGRes[T] =
   except PNGError, IOError, NZError:
     result.err(getCurrentExceptionMsg())
 
-proc decodePNG24*(T: type, input: T, settings = PNGDecoder(nil)): PNGRes[T] =
+proc decodePNG24Impl*[T](input: T, settings = PNGDecoder(nil)): PNGRes[T] =
   try:
     when T is string:
       var s = newStringStream(input)
@@ -1920,16 +1920,28 @@ when not defined(js):
     if res.isOk: result = res.get()
     else: debugEcho res.error()
 
-proc decodePNG32*(input: string, settings = PNGDecoder(nil)): PNGResult[string] =
-  let res = decodePNG32(string, input, settings)
+proc decodePNG32Legacy*(input: string, settings = PNGDecoder(nil)): PNGResult[string] =
+  let res = decodePNG32Impl(input, settings)
   if res.isOk: result = res.get()
   else: debugEcho res.error()
 
-proc decodePNG24*(input: string, settings = PNGDecoder(nil)): PNGResult[string] =
-  let res = decodePNG24(string, input, settings)
+proc decodePNG24Legacy*(input: string, settings = PNGDecoder(nil)): PNGResult[string] =
+  let res = decodePNG24Impl(input, settings)
   if res.isOk: result = res.get()
   else: debugEcho res.error()
 
+template decodePNG32*[T](input: T, settings = PNGDecoder(nil)): untyped =
+  when T is string:
+    decodePNG32Legacy(input, settings)
+  else:
+    decodePNG32Impl(input, settings)
+
+template decodePNG24*[T](input: T, settings = PNGDecoder(nil)): untyped =
+  when T is string:
+    decodePNG24Legacy(input, settings)
+  else:
+    decodePNG24Impl(input, settings)
+
 #Encoder/Decoder demarcation line-----------------------------
 
 type