diff --git a/src/errors/AddressErrors.ts b/src/errors/AddressErrors.ts
new file mode 100644
index 0000000..300bb31
--- /dev/null
+++ b/src/errors/AddressErrors.ts
@@ -0,0 +1,57 @@
+import { IsString } from 'class-validator';
+import { BadRequestError } from 'routing-controllers';
+
+/**
+ * Error to throw when an address's postal code fails validation.
+ */
+export class AddressPostalCodeInvalidError extends BadRequestError {
+	@IsString()
+	name = "AddressPostalCodeInvalidError"
+
+	@IsString()
+	message = "The postal code you provided is invalid. \n Please check if your postal code follows the postal code validation guidelines."
+}
+
+/**
+ * Error to throw when an non-empty address's first line isn't set.
+ */
+export class AddressFirstLineEmptyError extends BadRequestError {
+	@IsString()
+	name = "AddressFirstLineEmptyError"
+
+	@IsString()
+	message = "You provided a empty first address line. \n If you want an empty address please set all propertys to null. \n For non-empty addresses the following fields have to be set: address1, postalcode, city, country"
+}
+
+/**
+ * Error to throw when an non-empty address's postal code isn't set.
+ */
+export class AddressPostalCodeEmptyError extends BadRequestError {
+	@IsString()
+	name = "AddressPostalCodeEmptyError"
+
+	@IsString()
+	message = "You provided a empty postal code. \n If you want an empty address please set all propertys to null. \n For non-empty addresses the following fields have to be set: address1, postalcode, city, country"
+}
+
+/**
+ * Error to throw when an non-empty address's city isn't set.
+ */
+export class AddressCityEmptyError extends BadRequestError {
+	@IsString()
+	name = "AddressCityEmptyError"
+
+	@IsString()
+	message = "You provided a empty city. \n If you want an empty address please set all propertys to null. \n For non-empty addresses the following fields have to be set: address1, postalcode, city, country"
+}
+
+/**
+ * Error to throw when an non-empty address's country isn't set.
+ */
+export class AddressCountryEmptyError extends BadRequestError {
+	@IsString()
+	name = "AddressCountryEmptyError"
+
+	@IsString()
+	message = "You provided a empty country. \n If you want an empty address please set all propertys to null. \n For non-empty addresses the following fields have to be set: address1, postalcode, city, country"
+}
\ No newline at end of file
diff --git a/src/models/Address.ts b/src/models/Address.ts
new file mode 100644
index 0000000..dc66f10
--- /dev/null
+++ b/src/models/Address.ts
@@ -0,0 +1,80 @@
+import {
+  IsPostalCode,
+  IsString
+} from "class-validator";
+import ValidatorJS from 'validator';
+import { config } from '../../config';
+import { AddressCityEmptyError, AddressCountryEmptyError, AddressFirstLineEmptyError, AddressPostalCodeEmptyError, AddressPostalCodeInvalidError } from '../../errors/AddressErrors';
+
+/**
+ * Defines the Address class.
+ * Implemented this way to prevent any formatting differences.
+*/
+export class Address {
+  /**
+   * The address's first line.
+   * Containing the street and house number.
+   */
+  @IsString()
+  address1?: string;
+
+  /**
+   * The address's second line.
+   * Containing optional information.
+   */
+  @IsString()
+  address2?: string;
+
+  /**
+   * The address's postal code.
+   * This will get checked against the postal code syntax for the configured country.
+   */
+  @IsString()
+  @IsPostalCode(config.postalcode_validation_countrycode)
+  postalcode: string;
+
+  /**
+   * The address's city.
+   */
+  @IsString()
+  city: string;
+
+  /**
+   * The address's country.
+   */
+  @IsString()
+  country: string;
+
+  public reset() {
+    this.address1 = null;
+    this.address2 = null;
+    this.city = null;
+    this.country = null;
+    this.postalcode = null;
+  }
+
+  /**
+   * Checks if this is a valid address
+   */
+  public static isValidAddress(address: Address): Boolean {
+    if (address == null) { return false; }
+    if (address.address1 == null || address.city == null || address.country == null || address.postalcode == null) { return false; }
+    if (ValidatorJS.isPostalCode(address.postalcode, config.postalcode_validation_countrycode) == false) { return false; }
+    return true;
+  }
+
+  /**
+   * This function validates addresses.
+   * This is a workaround for non-existant class validation for embedded entities.
+   * @param address The address that shall get validated.
+   */
+  public static validate(address: Address) {
+    if (address == null) { return; }
+    if (address.address1 == null && address.city == null && address.country == null && address.postalcode == null) { return; }
+    if (address.address1 == null) { throw new AddressFirstLineEmptyError(); }
+    if (address.postalcode == null) { throw new AddressPostalCodeEmptyError(); }
+    if (address.city == null) { throw new AddressCityEmptyError(); }
+    if (address.country == null) { throw new AddressCountryEmptyError(); }
+    if (ValidatorJS.isPostalCode(address.postalcode.toString(), config.postalcode_validation_countrycode) == false) { throw new AddressPostalCodeInvalidError(); }
+  }
+}
diff --git a/src/models/CertificateRunner.ts b/src/models/CertificateRunner.ts
new file mode 100644
index 0000000..a30b356
--- /dev/null
+++ b/src/models/CertificateRunner.ts
@@ -0,0 +1,16 @@
+import {
+    IsArray
+} from "class-validator";
+import { DistanceDonation } from './DistanceDonation';
+import { Runner } from './Runner';
+
+/**
+ * Defines the certificate runner class (from which the runner certificates get generated).
+*/
+export class CertificateRunner extends Runner {
+    /**
+     * Array containing all distance donations associated with the runner.
+     */
+    @IsArray()
+    distanceDonations: DistanceDonation[];
+}
diff --git a/src/models/DistanceDonation.ts b/src/models/DistanceDonation.ts
new file mode 100644
index 0000000..a4e35e1
--- /dev/null
+++ b/src/models/DistanceDonation.ts
@@ -0,0 +1,40 @@
+import { IsInt, IsNotEmpty, IsObject, IsPositive } from "class-validator";
+import { Donation } from "./Donation";
+import { Runner } from "./Runner";
+
+/**
+ * Defines the DistanceDonation class.
+ * For distanceDonations a donor pledges to donate a certain amount for each kilometer ran by a runner.
+*/
+export class DistanceDonation extends Donation {
+  /**
+   * The donation's associated runner.
+   * Used as the source of the donation's distance.
+   */
+  @IsObject()
+  @IsNotEmpty()
+  runner: Runner;
+
+  /**
+   * The donation's amount donated per distance.
+   * The amount the donor set to be donated per kilometer that the runner ran.
+   */
+  @IsInt()
+  @IsPositive()
+  amountPerDistance: number;
+
+  /**
+   * The donation's amount in cents (or whatever your currency's smallest unit is.).
+   * Get's calculated from the runner's distance ran and the amount donated per kilometer.
+   */
+  public get amount(): number {
+    let calculatedAmount = 0;
+    try {
+      calculatedAmount = this.amountPerDistance * (this.runner.distance / 1000);
+    } catch (error) {
+      throw error;
+    }
+    return calculatedAmount;
+  }
+
+}
diff --git a/src/models/Donation.ts b/src/models/Donation.ts
new file mode 100644
index 0000000..1beaf0c
--- /dev/null
+++ b/src/models/Donation.ts
@@ -0,0 +1,32 @@
+import {
+  IsInt,
+  IsNotEmpty,
+  IsObject
+} from "class-validator";
+import { Donor } from './Donor';
+
+/**
+ * Defines the Donation base calss.
+ * A donation just associates a donor with a donation amount.
+ * The specifics of the amoun's determination has to be implemented in child classes.
+*/
+export abstract class Donation {
+  /**
+   * Autogenerated unique id (primary key).
+   */
+  @IsInt()
+  id: number;
+
+  /**
+   * The donations's donor.
+   */
+  @IsNotEmpty()
+  @IsObject()
+  donor: Donor;
+
+  /**
+   * The donation's amount in cents (or whatever your currency's smallest unit is.).
+   * The exact implementation may differ for each type of donation.
+   */
+  public abstract get amount(): number;
+}
\ No newline at end of file
diff --git a/src/models/Donor.ts b/src/models/Donor.ts
new file mode 100644
index 0000000..cb9d9df
--- /dev/null
+++ b/src/models/Donor.ts
@@ -0,0 +1,37 @@
+import {
+
+    IsInt,
+
+
+
+    IsString
+} from "class-validator";
+
+/**
+ * Defines the Donor class.
+*/
+export class Donor {
+    /**
+     * The donor's id.
+     */
+    @IsInt()
+    id: number;
+
+    /**
+     * The donor's first name.
+     */
+    @IsString()
+    firstname: string;
+
+    /**
+     * The donor's middle name.
+     */
+    @IsString()
+    middlename?: string;
+
+    /**
+     * The donor's last name.
+     */
+    @IsString()
+    lastname: string;
+}
diff --git a/src/models/FixedDonation.ts b/src/models/FixedDonation.ts
new file mode 100644
index 0000000..18c8a23
--- /dev/null
+++ b/src/models/FixedDonation.ts
@@ -0,0 +1,16 @@
+import { IsInt, IsPositive } from "class-validator";
+import { Donation } from "./Donation";
+
+/**
+ * Defines the FixedDonation entity.
+ * In the past there was no easy way to track fixed donations (eg. for creating donation receipts).
+*/
+export class FixedDonation extends Donation {
+
+  /**
+   * The donation's amount in cents (or whatever your currency's smallest unit is.).
+   */
+  @IsInt()
+  @IsPositive()
+  amount: number;
+}
\ No newline at end of file
diff --git a/src/models/Runner.ts b/src/models/Runner.ts
new file mode 100644
index 0000000..f7968a8
--- /dev/null
+++ b/src/models/Runner.ts
@@ -0,0 +1,47 @@
+import {
+    IsInt,
+    IsObject,
+    IsString
+} from "class-validator";
+import { RunnerGroup } from './RunnerGroup';
+
+/**
+ * Defines the runner class (from which the runner sponsoring contracts get generated).
+*/
+export class Runner {
+    /**
+     * The runner's id.
+     */
+    @IsInt()
+    id: number;
+
+    /**
+     * The runner's first name.
+     */
+    @IsString()
+    firstname: string;
+
+    /**
+     * The runner's middle name.
+     */
+    @IsString()
+    middlename?: string;
+
+    /**
+     * The runner's last name.
+     */
+    @IsString()
+    lastname: string;
+
+    /**
+     * The runner's group.
+     */
+    @IsObject()
+    group: RunnerGroup;
+
+    /**
+     * The total distance ran by the runner.
+     */
+    @IsInt()
+    distance: number;
+}
diff --git a/src/models/RunnerCard.ts b/src/models/RunnerCard.ts
new file mode 100644
index 0000000..3a4cffb
--- /dev/null
+++ b/src/models/RunnerCard.ts
@@ -0,0 +1,33 @@
+import {
+    IsEAN,
+    IsInt,
+    IsNotEmpty,
+    IsObject,
+    IsString
+} from "class-validator";
+import { Runner } from './Runner';
+
+/**
+ * Defines the runner card class (used to create runner card pdfs).
+*/
+export class RunnerCard {
+    /**
+     * The cards's id.
+     */
+    @IsInt()
+    id: number;
+
+    /**
+     * The card's associated runner.
+     */
+    @IsObject()
+    runner: Runner | null;
+
+    /**
+     * The card's code.
+     */
+    @IsEAN()
+    @IsString()
+    @IsNotEmpty()
+    code: string;
+}
diff --git a/src/models/RunnerGroup.ts b/src/models/RunnerGroup.ts
new file mode 100644
index 0000000..f50a179
--- /dev/null
+++ b/src/models/RunnerGroup.ts
@@ -0,0 +1,36 @@
+import { IsInt, IsNotEmpty, IsObject, IsOptional, IsString } from "class-validator";
+
+/**
+ * Defines the runner group class - a simplified version of the backend's ResponseRunnerTeam/-Organization
+*/
+export abstract class RunnerGroup {
+    /**
+     * The group's id.
+     */
+    @IsInt()
+    @IsNotEmpty()
+    id: number;;
+
+    /**
+     * The group's name.
+     */
+    @IsString()
+    @IsNotEmpty()
+    name: string;
+
+    /**
+     * The group's parent group.
+     * If it is set this implies that the object is a team.
+     */
+    @IsObject()
+    @IsOptional()
+    parentGroup?: RunnerGroup
+
+    /**
+     * Returns the groups full name in the format: org.name/team.name (or just org).
+     */
+    public get fullName(): string {
+        if (!this.parentGroup) { return this.name; }
+        return `${this.name}/${this.parentGroup.fullName}`;
+    }
+}