diff --git a/libimagtag/Cargo.toml b/libimagtag/Cargo.toml
new file mode 100644
index 00000000..0fd71402
--- /dev/null
+++ b/libimagtag/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "libimagtag"
+version = "0.1.0"
+authors = ["Matthias Beyer <mail@beyermatthias.de>"]
+
+[dependencies]
+clap = "2.1.1"
+log = "0.3.5"
+regex = "0.1.47"
+toml = "0.1.25"
+
+[dependencies.libimagstore]
+path = "../libimagstore"
+
diff --git a/libimagtag/src/error.rs b/libimagtag/src/error.rs
new file mode 100644
index 00000000..ed15e283
--- /dev/null
+++ b/libimagtag/src/error.rs
@@ -0,0 +1,70 @@
+use std::error::Error;
+use std::fmt::Error as FmtError;
+use std::clone::Clone;
+use std::fmt::{Debug, Display, Formatter};
+use std::fmt;
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum TagErrorKind {
+    TagTypeError,
+    HeaderReadError,
+    HeaderWriteError,
+    NotATag,
+}
+
+fn tag_error_type_as_str(e: &TagErrorKind) -> &'static str {
+    match e {
+        &TagErrorKind::TagTypeError     => "Entry Header Tag Type wrong",
+        &TagErrorKind::HeaderReadError  => "Error while reading entry header",
+        &TagErrorKind::HeaderWriteError => "Error while writing entry header",
+        &TagErrorKind::NotATag          => "String is not a tag",
+    }
+}
+
+impl Display for TagErrorKind {
+
+    fn fmt(&self, fmt: &mut Formatter) -> Result<(), FmtError> {
+        try!(write!(fmt, "{}", tag_error_type_as_str(self)));
+        Ok(())
+    }
+
+}
+
+#[derive(Debug)]
+pub struct TagError {
+    kind: TagErrorKind,
+    cause: Option<Box<Error>>,
+}
+
+impl TagError {
+
+    pub fn new(errtype: TagErrorKind, cause: Option<Box<Error>>) -> TagError {
+        TagError {
+            kind: errtype,
+            cause: cause,
+        }
+    }
+
+}
+
+impl Display for TagError {
+
+    fn fmt(&self, fmt: &mut Formatter) -> Result<(), FmtError> {
+        try!(write!(fmt, "[{}]", tag_error_type_as_str(&self.kind.clone())));
+        Ok(())
+    }
+
+}
+
+impl Error for TagError {
+
+    fn description(&self) -> &str {
+        tag_error_type_as_str(&self.kind.clone())
+    }
+
+    fn cause(&self) -> Option<&Error> {
+        self.cause.as_ref().map(|e| &**e)
+    }
+
+}
+
diff --git a/libimagtag/src/lib.rs b/libimagtag/src/lib.rs
new file mode 100644
index 00000000..f4d1c543
--- /dev/null
+++ b/libimagtag/src/lib.rs
@@ -0,0 +1,14 @@
+extern crate clap;
+#[macro_use] extern crate log;
+extern crate regex;
+extern crate toml;
+
+extern crate libimagstore;
+
+pub mod error;
+pub mod result;
+pub mod tag;
+pub mod tagable;
+pub mod util;
+pub mod ui;
+
diff --git a/libimagtag/src/result.rs b/libimagtag/src/result.rs
new file mode 100644
index 00000000..a01166ca
--- /dev/null
+++ b/libimagtag/src/result.rs
@@ -0,0 +1,6 @@
+use std::result::Result as RResult;
+
+use error::TagError;
+
+pub type Result<T> = RResult<T, TagError>;
+
diff --git a/libimagtag/src/tag.rs b/libimagtag/src/tag.rs
new file mode 100644
index 00000000..cba2322e
--- /dev/null
+++ b/libimagtag/src/tag.rs
@@ -0,0 +1 @@
+pub type Tag = String;
diff --git a/libimagtag/src/tagable.rs b/libimagtag/src/tagable.rs
new file mode 100644
index 00000000..f38f49d6
--- /dev/null
+++ b/libimagtag/src/tagable.rs
@@ -0,0 +1,165 @@
+use libimagstore::store::{Entry, EntryHeader};
+
+use error::{TagError, TagErrorKind};
+use result::Result;
+use tag::Tag;
+use util::is_tag;
+
+use toml::Value;
+
+pub trait Tagable {
+
+    fn get_tags(&self) -> Result<Vec<Tag>>;
+    fn set_tags(&mut self, ts: Vec<Tag>) -> Result<()>;
+
+    fn add_tag(&mut self, t: Tag) -> Result<()>;
+    fn remove_tag(&mut self, t: Tag) -> Result<()>;
+
+    fn has_tag(&self, t: &Tag) -> Result<bool>;
+    fn has_tags(&self, ts: &Vec<Tag>) -> Result<bool>;
+
+}
+
+impl Tagable for EntryHeader {
+
+    fn get_tags(&self) -> Result<Vec<Tag>> {
+        let tags = self.read("imag.tags");
+        if tags.is_err() {
+            let kind = TagErrorKind::HeaderReadError;
+            return Err(TagError::new(kind, Some(Box::new(tags.err().unwrap()))));
+        }
+        let tags = tags.unwrap();
+
+        match tags {
+            Some(Value::Array(tags)) => {
+                if !tags.iter().all(|t| match t { &Value::String(_) => true, _ => false }) {
+                    return Err(TagError::new(TagErrorKind::TagTypeError, None));
+                }
+                if tags.iter().any(|t| match t {
+                    &Value::String(ref s) => !is_tag(&s),
+                    _ => unreachable!()})
+                {
+                    return Err(TagError::new(TagErrorKind::NotATag, None));
+                }
+
+                Ok(tags.iter()
+                    .cloned()
+                    .map(|t| {
+                        match t {
+                           Value::String(s) => s,
+                           _ => unreachable!(),
+                        }
+                    })
+                    .collect())
+            },
+            None => Ok(vec![]),
+            _ => Err(TagError::new(TagErrorKind::TagTypeError, None)),
+        }
+    }
+
+    fn set_tags(&mut self, ts: Vec<Tag>) -> Result<()> {
+        if ts.iter().any(|tag| !is_tag(tag)) {
+            debug!("Not a tag: '{}'", ts.iter().filter(|t| !is_tag(t)).next().unwrap());
+            return Err(TagError::new(TagErrorKind::NotATag, None));
+        }
+
+        let a = ts.iter().map(|t| Value::String(t.clone())).collect();
+        self.set("imag.tags", Value::Array(a))
+            .map(|_| ())
+            .map_err(|e| TagError::new(TagErrorKind::HeaderWriteError, Some(Box::new(e))))
+    }
+
+    fn add_tag(&mut self, t: Tag) -> Result<()> {
+        if !is_tag(&t) {
+            debug!("Not a tag: '{}'", t);
+            return Err(TagError::new(TagErrorKind::NotATag, None));
+        }
+
+        self.get_tags()
+            .map(|mut tags| {
+                tags.push(t);
+                self.set_tags(tags)
+            })
+            .map(|_| ())
+    }
+
+    fn remove_tag(&mut self, t: Tag) -> Result<()> {
+        if !is_tag(&t) {
+            debug!("Not a tag: '{}'", t);
+            return Err(TagError::new(TagErrorKind::NotATag, None));
+        }
+
+        self.get_tags()
+            .map(|mut tags| {
+                tags.retain(|tag| tag.clone() != t);
+                self.set_tags(tags)
+            })
+            .map(|_| ())
+    }
+
+    fn has_tag(&self, t: &Tag) -> Result<bool> {
+        let tags = self.read("imag.tags");
+        if tags.is_err() {
+            let kind = TagErrorKind::HeaderReadError;
+            return Err(TagError::new(kind, Some(Box::new(tags.err().unwrap()))));
+        }
+        let tags = tags.unwrap();
+
+        if !tags.iter().all(|t| match t { &Value::String(_) => true, _ => false }) {
+            return Err(TagError::new(TagErrorKind::TagTypeError, None));
+        }
+
+        Ok(tags
+           .iter()
+           .any(|tag| {
+               match tag {
+                   &Value::String(ref s) => { s == t },
+                   _ => unreachable!()
+               }
+           }))
+    }
+
+    fn has_tags(&self, tags: &Vec<Tag>) -> Result<bool> {
+        let mut result = true;
+        for tag in tags {
+            let check = self.has_tag(tag);
+            if check.is_err() {
+                return Err(check.err().unwrap());
+            }
+            let check = check.unwrap();
+
+            result = result && check;
+        }
+
+        Ok(result)
+    }
+
+}
+
+impl Tagable for Entry {
+
+    fn get_tags(&self) -> Result<Vec<Tag>> {
+        self.get_header().get_tags()
+    }
+
+    fn set_tags(&mut self, ts: Vec<Tag>) -> Result<()> {
+        self.get_header_mut().set_tags(ts)
+    }
+
+    fn add_tag(&mut self, t: Tag) -> Result<()> {
+        self.get_header_mut().add_tag(t)
+    }
+
+    fn remove_tag(&mut self, t: Tag) -> Result<()> {
+        self.get_header_mut().remove_tag(t)
+    }
+
+    fn has_tag(&self, t: &Tag) -> Result<bool> {
+        self.get_header().has_tag(t)
+    }
+
+    fn has_tags(&self, ts: &Vec<Tag>) -> Result<bool> {
+        self.get_header().has_tags(ts)
+    }
+
+}
diff --git a/libimagtag/src/ui.rs b/libimagtag/src/ui.rs
new file mode 100644
index 00000000..e889e224
--- /dev/null
+++ b/libimagtag/src/ui.rs
@@ -0,0 +1,70 @@
+use clap::{Arg, ArgMatches, App, SubCommand};
+
+use tag::Tag;
+
+/// Generates a clap::SubCommand to be integrated in the commandline-ui builder for building a
+/// "tags --add foo --remove bar" subcommand to do tagging action.
+pub fn tag_subcommand<'a, 'b>() -> App<'a, 'b> {
+    SubCommand::with_name("tags")
+        .author("Matthias Beyer <mail@beyermatthias.de>")
+        .version("0.1")
+        .about("Add or remove tags")
+
+        .arg(Arg::with_name("add-tags")
+             .short("a")
+             .long("add")
+             .takes_value(true)
+             .multiple(true)
+             .help("Add tags, seperated by comma or by specifying multiple times"))
+
+        .arg(Arg::with_name("remove-tags")
+             .short("r")
+             .long("remove")
+             .takes_value(true)
+             .multiple(true)
+             .help("Remove tags, seperated by comma or by specifying multiple times"))
+}
+
+/// Generates a clap::Arg which can be integrated into the commandline-ui builder for building a
+/// "-t" or "--tags" argument which takes values for tagging actions (add, remove)
+pub fn tag_argument<'a, 'b>() -> Arg<'a, 'b> {
+    Arg::with_name("specify-tags")
+        .short("t")
+        .long("tags")
+        .takes_value(true)
+        .multiple(true)
+        .help("Add or remove tags, prefixed by '+' (for adding) or '-' (for removing)")
+}
+
+/// Get the tags which should be added from the commandline
+///
+/// Returns none if the argument was not specified
+pub fn get_add_tags(matches: &ArgMatches) -> Option<Vec<Tag>> {
+    extract_tags(matches, "add-tags", '+')
+}
+
+/// Get the tags which should be removed from the commandline
+///
+/// Returns none if the argument was not specified
+pub fn get_remove_tags(matches: &ArgMatches) -> Option<Vec<Tag>> {
+    extract_tags(matches, "remove-tags", '-')
+}
+
+fn extract_tags(matches: &ArgMatches, specifier: &str, specchar: char) -> Option<Vec<Tag>> {
+    if let Some(submatch) = matches.subcommand_matches("tags") {
+        submatch.values_of(specifier)
+            .map(|values| values.map(String::from).collect())
+    } else {
+        matches.values_of("specify-tags")
+            .map(|argmatches| {
+                argmatches
+                    .map(String::from)
+                    .filter(|s| s.chars().next() == Some(specchar))
+                    .map(|s| {
+                        String::from(s.split_at(1).1)
+                    })
+                    .collect()
+            })
+    }
+}
+
diff --git a/libimagtag/src/util.rs b/libimagtag/src/util.rs
new file mode 100644
index 00000000..caa32539
--- /dev/null
+++ b/libimagtag/src/util.rs
@@ -0,0 +1,5 @@
+use regex::Regex;
+
+pub fn is_tag(s: &String) -> bool {
+    Regex::new("^[a-zA-Z]([a-zA-Z0-9_-]*)$").unwrap().captures(&s[..]).is_some()
+}