diff --git a/backend/combine/combine.go b/backend/combine/combine.go
index 9f5713ff2..74384fb48 100644
--- a/backend/combine/combine.go
+++ b/backend/combine/combine.go
@@ -914,7 +914,7 @@ func (f *Fs) PublicLink(ctx context.Context, remote string, expire fs.Duration,
 	return do(ctx, uRemote, expire, unlink)
 }
 
-// Put in to the remote path with the modTime given of the given size
+// PutUnchecked in to the remote path with the modTime given of the given size
 //
 // May create the object even if it returns an error - if so
 // will return the object and the error, otherwise will return
diff --git a/backend/protondrive/protondrive.go b/backend/protondrive/protondrive.go
index 187d2529a..04f9573a1 100644
--- a/backend/protondrive/protondrive.go
+++ b/backend/protondrive/protondrive.go
@@ -1,3 +1,4 @@
+// Package protondrive implements the Proton Drive backend
 package protondrive
 
 import (
@@ -45,8 +46,8 @@ const (
 )
 
 var (
-	ErrCanNotUploadFileWithUnknownSize = errors.New("proton Drive can't upload files with unknown size")
-	ErrCanNotPurgeRootDirectory        = errors.New("can't purge root directory")
+	errCanNotUploadFileWithUnknownSize = errors.New("proton Drive can't upload files with unknown size")
+	errCanNotPurgeRootDirectory        = errors.New("can't purge root directory")
 
 	// for the auth/deauth handler
 	_mapper        configmap.Mapper
@@ -569,12 +570,10 @@ func (f *Fs) List(ctx context.Context, dir string) (fs.DirEntries, error) {
 	return entries, nil
 }
 
-// DirCacher describes an interface for doing the low level directory work
+// FindLeaf finds a directory of name leaf in the folder with ID pathID
 //
 // This should be implemented by the backend and will be called by the
 // dircache package when appropriate.
-//
-// FindLeaf finds a directory of name leaf in the folder with ID pathID
 func (f *Fs) FindLeaf(ctx context.Context, pathID, leaf string) (string, bool, error) {
 	/* f.opt.Enc.FromStandardName(leaf) not required since the DirCache only process sanitized path */
 
@@ -593,12 +592,10 @@ func (f *Fs) FindLeaf(ctx context.Context, pathID, leaf string) (string, bool, e
 	return link.LinkID, true, nil
 }
 
-// DirCacher describes an interface for doing the low level directory work
+// CreateDir makes a directory with pathID as parent and name leaf
 //
 // This should be implemented by the backend and will be called by the
 // dircache package when appropriate.
-//
-// CreateDir makes a directory with pathID as parent and name leaf
 func (f *Fs) CreateDir(ctx context.Context, pathID, leaf string) (string, error) {
 	/* f.opt.Enc.FromStandardName(leaf) not required since the DirCache only process sanitized path */
 
@@ -626,7 +623,7 @@ func (f *Fs) CreateDir(ctx context.Context, pathID, leaf string) (string, error)
 func (f *Fs) Put(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (fs.Object, error) {
 	size := src.Size()
 	if size < 0 {
-		return nil, ErrCanNotUploadFileWithUnknownSize
+		return nil, errCanNotUploadFileWithUnknownSize
 	}
 
 	existingObj, err := f.NewObject(ctx, src.Remote())
@@ -725,7 +722,7 @@ func (f *Fs) DirCacheFlush() {
 	f.protonDrive.ClearCache()
 }
 
-// Returns the supported hash types of the filesystem
+// Hashes returns the supported hash types of the filesystem
 func (f *Fs) Hashes() hash.Set {
 	return hash.Set(hash.SHA1)
 }
@@ -887,7 +884,7 @@ func (o *Object) Open(ctx context.Context, options ...fs.OpenOption) (io.ReadClo
 func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) error {
 	size := src.Size()
 	if size < 0 {
-		return ErrCanNotUploadFileWithUnknownSize
+		return errCanNotUploadFileWithUnknownSize
 	}
 
 	remote := o.Remote()
@@ -945,7 +942,7 @@ func (f *Fs) Purge(ctx context.Context, dir string) error {
 	root := path.Join(f.root, dir)
 	if root == "" {
 		// we can't remove the root directory, but we can list the directory and delete every folder and file in here
-		return ErrCanNotPurgeRootDirectory
+		return errCanNotPurgeRootDirectory
 	}
 
 	folderLinkID, err := f.dirCache.FindDir(ctx, f.sanitizePath(dir), false)
diff --git a/fs/config/flags/flags.go b/fs/config/flags/flags.go
index b96f37834..ca20402d2 100644
--- a/fs/config/flags/flags.go
+++ b/fs/config/flags/flags.go
@@ -104,6 +104,7 @@ func (gs *Groups) AllRegistered() map[*pflag.Flag]struct{} {
 	return out
 }
 
+// All is the global stats Groups
 var All *Groups
 
 // Groups of flags for documentation purposes
diff --git a/fs/features.go b/fs/features.go
index 560b6edd9..46e7ef424 100644
--- a/fs/features.go
+++ b/fs/features.go
@@ -639,6 +639,7 @@ type OpenWriterAter interface {
 // OpenWriterAtFn describes the OpenWriterAt function pointer
 type OpenWriterAtFn func(ctx context.Context, remote string, size int64) (WriterAtCloser, error)
 
+// OpenChunkWriter is an option interface for Fs to implement chunked writing
 type OpenChunkWriter interface {
 	// OpenChunkWriter returns the chunk size and a ChunkWriter
 	//
@@ -650,6 +651,7 @@ type OpenChunkWriter interface {
 // OpenChunkWriterFn describes the OpenChunkWriter function pointer
 type OpenChunkWriterFn func(ctx context.Context, remote string, src ObjectInfo, options ...OpenOption) (chunkSize int64, writer ChunkWriter, err error)
 
+// ChunkWriter is returned by OpenChunkWriter to implement chunked writing
 type ChunkWriter interface {
 	// WriteChunk will write chunk number with reader bytes, where chunk number >= 0
 	WriteChunk(ctx context.Context, chunkNumber int, reader io.ReadSeeker) (bytesWritten int64, err error)
diff --git a/fs/open_options.go b/fs/open_options.go
index 288a36303..26d6d7053 100644
--- a/fs/open_options.go
+++ b/fs/open_options.go
@@ -276,18 +276,22 @@ func (o MetadataOption) Mandatory() bool {
 	return false
 }
 
+// ChunkOption defines an Option which returns a preferred chunk size
 type ChunkOption struct {
 	ChunkSize int64
 }
 
+// Header formats the option as an http header
 func (o *ChunkOption) Header() (key string, value string) {
 	return "chunkSize", fmt.Sprintf("%v", o.ChunkSize)
 }
 
+// Mandatory returns whether the option must be parsed or can be ignored
 func (o *ChunkOption) Mandatory() bool {
 	return false
 }
 
+// String formats the option into human-readable form
 func (o *ChunkOption) String() string {
 	return fmt.Sprintf("ChunkOption(%v)", o.ChunkSize)
 }
diff --git a/lib/multipart/multipart.go b/lib/multipart/multipart.go
index 774076119..e584041ef 100644
--- a/lib/multipart/multipart.go
+++ b/lib/multipart/multipart.go
@@ -1,3 +1,4 @@
+// Package multipart implements generic multipart uploading.
 package multipart
 
 import (
@@ -37,7 +38,7 @@ func getPool() *pool.Pool {
 	return bufferPool
 }
 
-// Get a pool.RW using the multipart pool
+// NewRW gets a pool.RW using the multipart pool
 func NewRW() *pool.RW {
 	return pool.NewRW(getPool())
 }
@@ -50,7 +51,7 @@ type UploadMultipartOptions struct {
 	LeavePartsOnError bool               // if set don't delete parts uploaded so far on error
 }
 
-// Do a generic multipart upload from src using f as OpenChunkWriter.
+// UploadMultipart does a generic multipart upload from src using f as OpenChunkWriter.
 //
 // in is read seqentially and chunks from it are uploaded in parallel.
 //
diff --git a/lib/proxy/socks.go b/lib/proxy/socks.go
index 607bf43a7..1f8e3c40a 100644
--- a/lib/proxy/socks.go
+++ b/lib/proxy/socks.go
@@ -1,3 +1,4 @@
+// Package proxy enables SOCKS5 proxy dialling
 package proxy
 
 import (