POST vs PUT Difference: Comparison Table, Use Cases, and Examples
| Aspect | PUT | POST |
|---|---|---|
| Resource URL needed? | Yes (known beforehand) | No (server generates it) |
| Idempotent? | Yes | No |
| Common Use | Create/replace at known URL, update | Create at unknown URL, form actions |
| Response Codes | 200, 201, 204 | 201, 200, 202, 204, others |
Difference Between POST and PUT Methods
The main difference between POST and PUT methods is resource handling. PUT requires you to know the resource's URL, making it ideal for updating or creating something at a specific address. POST is used when you want the server to decide the resource's URL, which is helpful for actions like creating new items where IDs are generated by the system.
Definitions and When to Use PUT vs POST
PUT is a method used to create or fully replace a resource at a known URL. You provide all the information about a resource, and the server either creates it (if new) or replaces the old version (if it exists). Use PUT when the client knows the resource location.
POST, on the other hand, is used to create a new resource when the client does not know the final URL. The server processes the information and generates a unique link (often an ID). POST can also perform other actions like submitting a form, uploading files, or processing data.
POST vs PUT Examples
PUT Example
Suppose we are tracking airline flights. To update the status of flight AA123, you use:
PUT /flights/AA123
Payload: { "status": "delayed" }
You already know the exact URL. The server either updates or creates "AA123" with your data.
POST Example
To create a new customer, where you don't know the customer's ID yet, you use:
POST /customers
Payload: { "name": "Riya", "email": "riya@email.com" }
The server creates a new customer and returns a link like /customers/1234.
Understanding Idempotency in PUT and POST
Idempotency means that repeating an operation has the same effect every time. PUT is idempotent: sending the same PUT request 100 times changes nothing beyond the first. POST is not idempotent: each new POST can create or change something new (like adding duplicate records).
- PUT example: Updating a user's email to the same address repeatedly always results in the same state.
- POST example: Submitting the same payment form 3 times might debit your account 3 times.
How POST and PUT Are Used in Real Life
In daily application development, use POST for creating new records, like registering a user or submitting a comment, where the resource's unique URL is set after creation. Use PUT to update a user's profile or replace an entire resource when you know its direct link.
RESTful CRUD Mapping: POST, PUT, GET, DELETE
In RESTful APIs, HTTP methods map to CRUD actions:
- GET – Read a resource (like viewing a user)
- POST – Create a new resource (like adding a comment)
- PUT – Update/replace a resource at a known address
- DELETE – Remove a resource
Choosing Between PUT and POST in APIs
Follow these guidelines to decide:
- Use PUT if you already know the exact URL (like /users/234) and want to store or update the full object.
- Use POST when resources have system-generated IDs or you’re adding to a collection (like /users) and let the server choose the URL.
Related Grammar and API Concepts
- Past Perfect Tense
- Grammar Rules
- Modal Verbs
- Auxiliary Verbs
- Pronouns - Interrogative
- Difference Between Was and Were
- Sentence Structure
- Transformation of Sentences
- Declarative Sentences
At Vedantu, we simplify technical grammar and web development concepts so students excel in school exams, competitive tests, or real programming tasks. Mastering POST and PUT differences makes your API usage clear and efficient.
In summary, understanding the difference between POST and PUT empowers students to apply the right HTTP methods in school, job interviews, and real-world projects. Remember, PUT is for creating or replacing at a known URL and is idempotent; POST is for creating when you don’t know the URL. Being clear with these builds strong English and coding fundamentals.
FAQs on Difference Between POST and PUT in REST API (With Examples)
1. What is the difference between POST and PUT in REST API?
The core difference between POST and PUT in a REST API lies in how they handle resource creation and updates. POST creates a new resource; the server assigns the ID. PUT updates or creates a resource at a specific known URL.
2. When should you use PUT instead of POST?
Use PUT when you know the exact location (URL) of the resource you want to update or create. It's ideal for scenarios where you're modifying an existing resource using a known identifier.
3. Are PUT and POST both idempotent methods?
No. Only PUT is idempotent. Idempotency means that making the same request multiple times has the same effect as making it once. Multiple PUT requests with identical data will produce the same result, whereas multiple POST requests will create multiple resources.
4. Can PUT be used to create new resources?
Yes, PUT can create a new resource if the resource does not already exist at the specified URL. However, it's generally more common to use POST for creating new resources as it allows the server to generate a unique identifier.
5. What is idempotency, and why is it required for PUT but not POST?
Idempotency in HTTP means that making the same request multiple times has the same effect as making it once. PUT needs this because it's meant for updating. Multiple updates with the same data should only reflect the final update. POST doesn't need this because each request usually creates something new.
6. Does POST require the resource URL?
No, POST typically does not require the full resource URL beforehand. The server generates this, usually including a newly created ID in the response.
7. What happens if you use POST to update a resource that already exists?
Using POST to update an existing resource is generally not the recommended approach. It might create a duplicate entry or behave unexpectedly, depending on the server's implementation. PUT is the correct method for updating resources.
8. How do server-generated keys affect POST and PUT selection?
Server-generated keys influence the choice between POST and PUT. If the server assigns a unique identifier (like an ID), use POST; if you already have the identifier and are targeting a specific resource location, use PUT.
9. Can you replace all fields of an object with PUT, or only some?
A PUT request typically replaces the entire resource representation at the specified URL. To update only certain fields, use the PATCH method instead.
10. What is the main difference between put and POST?
The key difference lies in resource handling. POST creates a new resource, while PUT updates or replaces an existing resource at a known location. PUT is idempotent; POST is not.
11. When to use GET vs POST vs put?
Use GET to retrieve data, POST to create new resources (server assigns ID), and PUT to update or replace existing resources at known URLs. PUT is idempotent, while POST is not.
12. What is the difference between POST and put in Salesforce?
In Salesforce, the difference between POST and PUT mirrors standard REST API behavior. POST creates new records, while PUT updates existing records, using the record ID as part of the URL. PUT is idempotent while POST is not.
