diff --git a/Claunia.Localization.Core/Claunia.Localization.Core.csproj b/Claunia.Localization.Core/Claunia.Localization.Core.csproj
new file mode 100644
index 0000000..185a24c
--- /dev/null
+++ b/Claunia.Localization.Core/Claunia.Localization.Core.csproj
@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>netstandard1.6</TargetFramework>
+    </PropertyGroup>
+
+</Project>
diff --git a/Claunia.Localization.Core/Language.cs b/Claunia.Localization.Core/Language.cs
new file mode 100644
index 0000000..15b76ad
--- /dev/null
+++ b/Claunia.Localization.Core/Language.cs
@@ -0,0 +1,32 @@
+namespace Claunia.Localization.Core
+{
+    /// <summary>Enumerates programming languages for parameters</summary>
+    public enum Language
+    {
+        C,
+        ObjectiveC,
+        CSharp,
+        Shell,
+        Python,
+        Lisp,
+        EmacsLisp,
+        PythonBraced,
+        Librep,
+        Scheme,
+        Smalltalk,
+        Java,
+        Awk,
+        ObjectPascal,
+        Ycp,
+        Tcl,
+        Perl,
+        Php,
+        GccInternal,
+        GfcInternal,
+        Qt,
+        QtPlural,
+        Kde,
+        Boost,
+        JavaScript
+    }
+}
\ No newline at end of file
diff --git a/Claunia.Localization.Core/Localization.cs b/Claunia.Localization.Core/Localization.cs
new file mode 100644
index 0000000..9469e25
--- /dev/null
+++ b/Claunia.Localization.Core/Localization.cs
@@ -0,0 +1,101 @@
+using System;
+using System.Collections.ObjectModel;
+using System.Linq;
+
+namespace Claunia.Localization.Core
+{
+    /// <summary>
+    ///     Represents the localization
+    /// </summary>
+    public class Localization
+    {
+        readonly ObservableCollection<Message>    messages;
+        readonly ObservableCollection<Translator> translators;
+
+        public Localization()
+        {
+            Creation                      =  DateTime.UtcNow;
+            LastWritten                   =  DateTime.UtcNow;
+            Project                       =  new Project();
+            Project.ProjectModified       += OnModified;
+            translators                   =  new ObservableCollection<Translator>();
+            Translators                   =  new ReadOnlyObservableCollection<Translator>(translators);
+            translators.CollectionChanged += OnModified;
+            messages                      =  new ObservableCollection<Message>();
+            Messages                      =  new ReadOnlyObservableCollection<Message>(messages);
+            messages.CollectionChanged    += OnModified;
+        }
+
+        /// <summary>Date this localization has been created</summary>
+        public DateTime Creation { get; }
+        /// <summary>Date this localization has been modified</summary>
+        public DateTime LastWritten { get; private set; }
+        /// <summary>Project this localization belongs to</summary>
+        public Project Project { get; }
+        /// <summary>List of translators that have worked in this localization</summary>
+        public ReadOnlyObservableCollection<Translator> Translators { get; }
+        /// <summary>
+        ///     List of messages present in this localization
+        /// </summary>
+        public ReadOnlyObservableCollection<Message> Messages { get; }
+
+        void OnModified(object sender, EventArgs args)
+        {
+            LastWritten = DateTime.UtcNow;
+        }
+
+        /// <summary>
+        ///     Adds a new translator to the localization
+        /// </summary>
+        /// <param name="name">Translator full name, english-form, in ASCII</param>
+        /// <param name="email">Translator e-mail</param>
+        /// <param name="nativeName">Translator full name, in native form</param>
+        /// <returns>The new translator</returns>
+        public Translator NewTranslator(string name, string email, string nativeName = null)
+        {
+            int        id         = translators.Max(t => t.Id) + 1;
+            Translator translator = new Translator(id) {Name = name, Email = email};
+            translator.Modified += OnModified;
+
+            translators.Add(translator);
+
+            return translator;
+        }
+
+        /// <summary>
+        ///     Removes a translator from the localization
+        /// </summary>
+        /// <param name="translator">Translator to remove</param>
+        /// <returns><c>true</c> if the translator has been removed successfully, <c>false</c> otherwise</returns>
+        public bool RemoveTranslator(Translator translator) => !(translator is null) && translators.Remove(translator);
+
+        /// <summary>
+        ///     Removes a translator from the localization
+        /// </summary>
+        /// <param name="id">ID of the translator to remove</param>
+        /// <returns><c>true</c> if the translator has been removed successfully, <c>false</c> otherwise</returns>
+        public bool RemoveTranslator(int id)
+        {
+            Translator translator = translators.FirstOrDefault(t => t.Id == id);
+            return !(translator is null) && translators.Remove(translator);
+        }
+
+        public Message NewMessage()
+        {
+            Message message = new Message();
+            message.Modified += OnModified;
+
+            messages.Add(message);
+
+            return message;
+        }
+
+        public bool RemoveMessage(Message message) => !(message is null) && messages.Remove(message);
+
+        public bool RemoveMessage(string id)
+        {
+            Message message = messages.FirstOrDefault(t => t.Id == id);
+            return !(message is null) && messages.Remove(message);
+        }
+    }
+}
\ No newline at end of file
diff --git a/Claunia.Localization.Core/LocalizedString.cs b/Claunia.Localization.Core/LocalizedString.cs
new file mode 100644
index 0000000..ebfbd45
--- /dev/null
+++ b/Claunia.Localization.Core/LocalizedString.cs
@@ -0,0 +1,103 @@
+using System;
+using System.Collections.ObjectModel;
+
+namespace Claunia.Localization.Core
+{
+    /// <summary>
+    ///     Represent a localized string
+    /// </summary>
+    public sealed class LocalizedString
+    {
+        readonly ObservableCollection<Plural> plurals;
+        string                                comments;
+        string                                locale;
+        internal EventHandler                 Modified;
+        string                                singular;
+        int?                                  translator;
+
+        internal LocalizedString()
+        {
+            plurals                   =  new ObservableCollection<Plural>();
+            plurals.CollectionChanged += (sender, args) => Modified?.Invoke(this, EventArgs.Empty);
+            Plurals                   =  new ReadOnlyObservableCollection<Plural>(plurals);
+        }
+
+        /// <summary>
+        ///     Contains the singular, or only, text for this string
+        /// </summary>
+        public string Singular
+        {
+            get => singular;
+            set
+            {
+                singular = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Which locale this string is in. Format is ll_CC with ll as ISO 639-2 language code and CC as ISO 3166 two letter
+        ///     uppercase country code. _CC can be omitted.
+        /// </summary>
+        public string Locale
+        {
+            get => locale;
+            set
+            {
+                locale = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     ID of the translator, in this localization, that wrote this string
+        /// </summary>
+        public int? Translator
+        {
+            get => translator;
+            set
+            {
+                translator = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Translator comments
+        /// </summary>
+        public string Comments
+        {
+            get => comments;
+            set
+            {
+                comments = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Plural forms for this string
+        /// </summary>
+        public ReadOnlyObservableCollection<Plural> Plurals { get; }
+
+        /// <summary>
+        ///     Initializes a new plural in this message
+        /// </summary>
+        /// <returns>The newly initialized plural</returns>
+        public Plural NewPlural()
+        {
+            Plural parameter = new Plural();
+            parameter.Modified += Modified;
+            plurals.Add(parameter);
+
+            return parameter;
+        }
+
+        /// <summary>
+        ///     Removes a plural
+        /// </summary>
+        /// <param name="parameter">The plural to remove</param>
+        /// <returns><c>true</c> if the plural string has been removed successfully, <c>false</c> otherwise</returns>
+        public bool RemovePlural(Plural parameter) => plurals.Remove(parameter);
+    }
+}
\ No newline at end of file
diff --git a/Claunia.Localization.Core/Message.cs b/Claunia.Localization.Core/Message.cs
new file mode 100644
index 0000000..1c6b8b4
--- /dev/null
+++ b/Claunia.Localization.Core/Message.cs
@@ -0,0 +1,150 @@
+using System;
+using System.Collections.ObjectModel;
+
+namespace Claunia.Localization.Core
+{
+    /// <summary>
+    ///     Represent a message and its translations
+    /// </summary>
+    public sealed class Message
+    {
+        readonly ObservableCollection<Parameter>       parameters;
+        readonly ObservableCollection<LocalizedString> translations;
+        string                                         comments;
+        string                                         context;
+        string                                         id;
+        internal EventHandler                          Modified;
+        string                                         previousContext;
+        string                                         reference;
+
+        internal Message()
+        {
+            Source                         =  new LocalizedString();
+            Source.Modified                += Modified;
+            translations                   =  new ObservableCollection<LocalizedString>();
+            translations.CollectionChanged += (sender, args) => Modified?.Invoke(this, EventArgs.Empty);
+            parameters                     =  new ObservableCollection<Parameter>();
+            parameters.CollectionChanged   += (sender, args) => Modified?.Invoke(this, EventArgs.Empty);
+            Translations                   =  new ReadOnlyObservableCollection<LocalizedString>(translations);
+            Parameters                     =  new ReadOnlyObservableCollection<Parameter>(parameters);
+        }
+
+        /// <summary>
+        ///     Describes the context where this message occurs
+        /// </summary>
+        public string Context
+        {
+            get => context;
+            set
+            {
+                context = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Describes the context where the previous version of this message occurred
+        /// </summary>
+        public string PreviousContext
+        {
+            get => previousContext;
+            set
+            {
+                previousContext = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Comments added by the original writer of the message
+        /// </summary>
+        public string Comments
+        {
+            get => comments;
+            set
+            {
+                comments = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Source code line reference or equivalent
+        /// </summary>
+        public string Reference
+        {
+            get => reference;
+            set
+            {
+                reference = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Unique identifier of this message
+        /// </summary>
+        public string Id
+        {
+            get => id;
+            set
+            {
+                id = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Original locale of this message
+        /// </summary>
+        public LocalizedString Source { get; }
+        /// <summary>
+        ///     List of translations
+        /// </summary>
+        public ReadOnlyObservableCollection<LocalizedString> Translations { get; }
+        /// <summary>
+        ///     List of parameters
+        /// </summary>
+        public ReadOnlyObservableCollection<Parameter> Parameters { get; }
+
+        /// <summary>
+        ///     Initializes a new localized string in this message
+        /// </summary>
+        /// <returns>The newly initialized localized string</returns>
+        public LocalizedString NewLocalizedString()
+        {
+            LocalizedString localizedString = new LocalizedString();
+            localizedString.Modified += Modified;
+            translations.Add(localizedString);
+
+            return localizedString;
+        }
+
+        /// <summary>
+        ///     Removes a localized string
+        /// </summary>
+        /// <param name="localizedString">The localized string to remove</param>
+        /// <returns><c>true</c> if the localized string has been removed successfully, <c>false</c> otherwise</returns>
+        public bool RemoveLocalizedString(LocalizedString localizedString) => translations.Remove(localizedString);
+
+        /// <summary>
+        ///     Initializes a new parameter in this message
+        /// </summary>
+        /// <returns>The newly initialized parameter</returns>
+        public Parameter NewParameter()
+        {
+            Parameter parameter = new Parameter();
+            parameter.Modified += Modified;
+            parameters.Add(parameter);
+
+            return parameter;
+        }
+
+        /// <summary>
+        ///     Removes a parameter
+        /// </summary>
+        /// <param name="parameter">The parameter to remove</param>
+        /// <returns><c>true</c> if the parameter string has been removed successfully, <c>false</c> otherwise</returns>
+        public bool RemoveParameter(Parameter parameter) => parameters.Remove(parameter);
+    }
+}
\ No newline at end of file
diff --git a/Claunia.Localization.Core/Parameter.cs b/Claunia.Localization.Core/Parameter.cs
new file mode 100644
index 0000000..75281f4
--- /dev/null
+++ b/Claunia.Localization.Core/Parameter.cs
@@ -0,0 +1,97 @@
+using System;
+
+namespace Claunia.Localization.Core
+{
+    /// <summary>
+    ///     Explanation of a parameter in a software string to help the translator understand the context and for translation
+    ///     helping software to be able to provide appropriate examples
+    /// </summary>
+    public class Parameter
+    {
+        string                description;
+        int                   index;
+        Language              language;
+        long?                 maximum;
+        long?                 minimum;
+        internal EventHandler Modified;
+        string                type;
+
+        /// <summary>
+        ///     Index of parameter in source message
+        /// </summary>
+        public int Index
+        {
+            get => index;
+            set
+            {
+                index = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Programming language for interpretation of messages
+        /// </summary>
+        public Language Language
+        {
+            get => language;
+            set
+            {
+                language = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Simple (single-word) description of parameter type
+        /// </summary>
+        public string Type
+        {
+            get => type;
+            set
+            {
+                type = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Minimum value the parameter can get
+        /// </summary>
+        public long? Minimum
+        {
+            get => minimum;
+            set
+            {
+                minimum = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Maximum value the parameter can get
+        /// </summary>
+        public long? Maximum
+        {
+            get => maximum;
+            set
+            {
+                maximum = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Description of the parameter
+        /// </summary>
+        public string Description
+        {
+            get => description;
+            set
+            {
+                description = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/Claunia.Localization.Core/Plural.cs b/Claunia.Localization.Core/Plural.cs
new file mode 100644
index 0000000..e0b33eb
--- /dev/null
+++ b/Claunia.Localization.Core/Plural.cs
@@ -0,0 +1,40 @@
+using System;
+
+namespace Claunia.Localization.Core
+{
+    /// <summary>
+    ///     Contains the plural forms of a string
+    /// </summary>
+    public class Plural
+    {
+        int                   items;
+        internal EventHandler Modified;
+        string                text;
+
+        /// <summary>
+        ///     Minimum number (inclusive) of items named to use this plural form
+        /// </summary>
+        public int Items
+        {
+            get => items;
+            set
+            {
+                items = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Plural form of the string
+        /// </summary>
+        public string Text
+        {
+            get => text;
+            set
+            {
+                text = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/Claunia.Localization.Core/Project.cs b/Claunia.Localization.Core/Project.cs
new file mode 100644
index 0000000..ff668e3
--- /dev/null
+++ b/Claunia.Localization.Core/Project.cs
@@ -0,0 +1,51 @@
+using System;
+
+namespace Claunia.Localization.Core
+{
+    public class Project
+    {
+        string name;
+
+        internal EventHandler ProjectModified;
+        string                url;
+        string                version;
+        /// <summary>
+        ///     Project name
+        /// </summary>
+        public string Name
+        {
+            get => name;
+            set
+            {
+                name = value;
+                ProjectModified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Project version
+        /// </summary>
+        public string Version
+        {
+            get => version;
+            set
+            {
+                version = value;
+                ProjectModified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Project URL
+        /// </summary>
+        public string Url
+        {
+            get => url;
+            set
+            {
+                url = value;
+                ProjectModified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/Claunia.Localization.Core/Translator.cs b/Claunia.Localization.Core/Translator.cs
new file mode 100644
index 0000000..c3d05bc
--- /dev/null
+++ b/Claunia.Localization.Core/Translator.cs
@@ -0,0 +1,63 @@
+using System;
+
+namespace Claunia.Localization.Core
+{
+    public class Translator
+    {
+        string                email;
+        internal EventHandler Modified;
+        string                name;
+        string                nativeName;
+
+        internal Translator(int id)
+        {
+            Id = id;
+        }
+
+        /// <summary>
+        ///     Translator ID, unique in the corresponding localization, and sequential
+        /// </summary>
+        public int Id { get; }
+
+        /// <summary>
+        ///     Translator e-mail
+        /// </summary>
+        public string Email
+        {
+            get => email;
+            set
+            {
+                email = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Translator name, in ASCII, english form
+        /// </summary>
+        public string Name
+        {
+            get => name;
+            set
+            {
+                name = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Translator full name in native form
+        /// </summary>
+        public string NativeName
+        {
+            get => nativeName ?? Name;
+            set
+            {
+                if(value == name) return;
+
+                nativeName = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/Claunia.Localization.sln b/Claunia.Localization.sln
index 8189da1..3c0961d 100644
--- a/Claunia.Localization.sln
+++ b/Claunia.Localization.sln
@@ -4,6 +4,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Claunia.Localization", "Cla
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Claunia.Localization.Desktop", "Claunia.Localization\Claunia.Localization.Desktop\Claunia.Localization.Desktop.csproj", "{258FEA96-4E93-4C8F-94EF-1319F93B350D}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Claunia.Localization.Core", "Claunia.Localization.Core\Claunia.Localization.Core.csproj", "{CFDFDFC7-9662-4C50-B86A-9E579ACD3DF9}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -20,5 +22,9 @@ Global
 		{258FEA96-4E93-4C8F-94EF-1319F93B350D}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{258FEA96-4E93-4C8F-94EF-1319F93B350D}.Release|Any CPU.Build.0 = Release|Any CPU
 		{258FEA96-4E93-4C8F-94EF-1319F93B350D}.Release|Any CPU.Deploy.0 = Release|Any CPU
+		{CFDFDFC7-9662-4C50-B86A-9E579ACD3DF9}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{CFDFDFC7-9662-4C50-B86A-9E579ACD3DF9}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{CFDFDFC7-9662-4C50-B86A-9E579ACD3DF9}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{CFDFDFC7-9662-4C50-B86A-9E579ACD3DF9}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal