Application period for the summer internships has ended, thanks for all the applicants! However, we have plenty of open roles in https://careers.wolt.com/en 🙂
Preliminary Assignment for backend / frontend internships. Welcome! We are delighted to see you applying. Now it's your time to shine.
NOTE! Please implement either backend OR frontend task, not both.
Technologies available per location:
- Helsinki 🇫🇮: Frontend (React + TS) OR Backend (Python or Kotlin)
- Berlin 🇩🇪: Frontend (React + TS) OR Backend (Python or Kotlin or Scala)
Please take your time, use the entire time available to complete this to the best of your ability - we do not prioritise submissions by speed!
The goal of the assignment is to showcase your coding skills and ability to develop features. This is a highly important part of the hiring process so it's crucial to put effort into this without making it too bloated. Reviewers will put weight on three main aspects: code quality, maintainability, and testing. Based on the results of the assignment review, we will make the decision on proceeding to the technical interview.
Your task is to write a delivery fee calculator. This code is needed when a customer is ready with their shopping cart and we’d like to show them how much the delivery will cost. The delivery price depends on the cart value, the number of items in the cart, the time of the order, and the delivery distance.
Rules for calculating a delivery fee
- If the cart value is less than 10€, a small order surcharge is added to the delivery price. The surcharge is the difference between the cart value and 10€. For example if the cart value is 8.90€, the surcharge will be 1.10€.
- A delivery fee for the first 1000 meters (=1km) is 2€. If the delivery distance is longer than that, 1€ is added for every additional 500 meters that the courier needs to travel before reaching the destination. Even if the distance would be shorter than 500 meters, the minimum fee is always 1€.
- Example 1: If the delivery distance is 1499 meters, the delivery fee is: 2€ base fee + 1€ for the additional 500 m => 3€
- Example 2: If the delivery distance is 1500 meters, the delivery fee is: 2€ base fee + 1€ for the additional 500 m => 3€
- Example 3: If the delivery distance is 1501 meters, the delivery fee is: 2€ base fee + 1€ for the first 500 m + 1€ for the second 500 m => 4€
- If the number of items is five or more, an additional 50 cent surcharge is added for each item above and including the fifth item. An extra "bulk" fee applies for more than 12 items of 1,20€
- Example 1: If the number of items is 4, no extra surcharge
- Example 2: If the number of items is 5, 50 cents surcharge is added
- Example 3: If the number of items is 10, 3€ surcharge (6 x 50 cents) is added
- Example 4: If the number of items is 13, 5,70€ surcharge is added ((9 * 50 cents) + 1,20€)
- Example 5: If the number of items is 14, 6,20€ surcharge is added ((10 * 50 cents) + 1,20€)
- The delivery fee can never be more than 15€, including possible surcharges.
- The delivery is free (0€) when the cart value is equal or more than 200€.
- During the Friday rush, 3 - 7 PM, the delivery fee (the total fee including possible surcharges) will be multiplied by 1.2x. However, the fee still cannot be more than the max (15€). Considering timezone, for simplicity, use UTC as a timezone in backend solutions (so Friday rush is 3 - 7 PM UTC). In frontend solutions, use the timezone of the browser (so Friday rush is 3 - 7 PM in the timezone of the browser).
When reviewing your code, we will focus on the part that fulfils the requirements explained above. We would love to see a well-tested and readable solution.
Pro tip: When you think you are ready with the assignment, take at least a few hours break, and then go through the code one more time before returning it.
Bundle everything into a Zip archive and upload it to Google Drive, Dropbox or similar and include the link in the application. Remember to check permissions! If we cannot access the file, we cannot review your code. Please don’t store your solution in a public GitHub repository during the application period.
A good check before sending your task is to unzip the Zip archive into a new folder and check that building and running the project works, using the steps you define in readme.md. Forgotten dependencies and instructions can sometimes happen even to the best of us.
Your task is to build an HTTP API which could be used for calculating the delivery fee.
Please use one of the programming languages available in the location you're applying to (Helsinki: Python / Kotlin & Berlin: Python / Kotlin / Scala). Feel free to use libraries / frameworks.
Note that your technology choice here defines the scope of the possible technical interview and your focus area if starting to work at Wolt 😊
Implement an HTTP API (single POST endpoint) which calculates the delivery fee based on the information in the request payload (JSON) and includes the calculated delivery fee in the response payload (JSON).
Example:
{"cart_value": 790, "delivery_distance": 2235, "number_of_items": 4, "time": "2024-01-15T13:00:00Z"}| Field | Type | Description | Example value |
|---|---|---|---|
| cart_value | Integer | Value of the shopping cart in cents. | 790 (790 cents = 7.90€) |
| delivery_distance | Integer | The distance between the store and customer’s location in meters. | 2235 (2235 meters = 2.235 km) |
| number_of_items | Integer | The number of items in the customer's shopping cart. | 4 (customer has 4 items in the cart) |
| time | String | Order time in UTC in ISO format. | 2024-01-15T13:00:00Z |
Example:
{"delivery_fee": 710}| Field | Type | Description | Example value |
|---|---|---|---|
| delivery_fee | Integer | Calculated delivery fee in cents. | 710 (710 cents = 7.10€) |
Build a delivery fee calculator web app using React and TypeScript.
Build a delivery fee calculator app which calculates a delivery fee based on user input and shows the calculated delivery fee to the user.
| Field | Type | Description | Example value |
|---|---|---|---|
| Cart value | Float | Value of the shopping cart in euros. | 20 |
| Delivery distance | Integer | The distance between the store and customer’s location in meters. | 2235 (2235 meters = 2.235 km) |
| Number of items | Integer | The number of items in the customer's shopping cart. | 4 (customer has 4 items in the cart) |
| Order time | Date + Time | The date/time when the order is being made (see rules-section how rush hours affect the delivery price) | You can choose the most suitable format |
When creating web interfaces, it's important to ensure accessibility and ease of testing. For each Field in the table above, ensure that the root element containing the value, typically an input element, includes a data-test-id attribute. This attribute is used for identifying elements during automated testing. The value of data-test-id should be the camelCase version of the Field listed in the table. For example, the field Cart value in the table should correspond to data-test-id="cartValue". For elements like custom datepickers that involve selecting a date via buttons, make sure there is also an input field, to ensure accessibility. The element containing the resulting fee that is calculated should also have a test id of data-test-id=fee.
Feel free to design and implement the user interface how you want. Below is an example of what it could look like.
When reviewing the assignment, we are focusing on the code quality and structure of your app. However, good UX & design will definitely give you bonus points. We also encourage you to consider accessibility in your implementation as that topic is close to our hearts here at Wolt. Crafting an accessible design and writing accessible code are the kind of good development practices we value.
