String Analyzer Service

A RESTful API that analyzes strings and stores their properties, supporting creation, retrieval, filtering (including natural language queries), and deletion.

---

Features

For every analyzed string, the API computes and stores:

Property	Description
length	Number of characters in the string
is_palindrome	Whether the string reads the same forwards and backwards (case-insensitive)
unique_characters	Number of distinct characters in the string
word_count	Number of whitespace-separated words
sha256_hash	SHA-256 hash for unique identification
character_frequency_map	A dictionary showing each character and its count

---

Endpoints Overview

1. POST /strings

Analyze and store a new string.

Request

{
  "value": "hello world"
}

Response (201 Created)

{
  "id": "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9", // sha256 hash
  "value": "hello world",
  "properties": {
    "length": 11,
    "is_palindrome": false,
    "unique_characters": 8,
    "word_count": 2,
    "character_frequency_map": {
      "h": 1,
      "e": 1,
      "l": 3,
      "o": 2,
      " ": 1,
      "w": 1,
      "r": 1,
      "d": 1
    },
    "sha256_hash": "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
  },
  "created_at": "2025-10-22T11:43:39.705Z"
}

Error Codes

• 400 – Missing or invalid "value" field
• 409 – String already exists
• 422 – Invalid type (non-string)

---

2. GET /strings/{string_value}

Retrieve details of a specific analyzed string.

Error Codes

• 404 – String not found

---

3. GET /strings

Retrieve all strings with optional filters.

Example

GET /strings?is_palindrome=true&min_length=5&max_length=20&word_count=2&contains_character=a

Response

{
  "data": [/* matching strings */],
  "count": 15,
  "filters_applied": {
    "is_palindrome": true,
    "min_length": 6,
    "max_length": 14,
    "word_count": 1,
    "contains_character": "b"
  }
}

Error Codes

• 400 – Invalid query parameter

---

4. GET /strings/filter-by-natural-language

Filter using plain English queries.

Example

GET /strings/filter-by-natural-languagequery=all%20single%20word%20palindromic%20strings%20that%20contain%20the%20first%20vowel

Response

{
  "data": [/* matches */],
  "count": 3,
  "interpreted_query": {
    "original": "all single word palindromic strings that contain the first vowel",
    "parsed_filters": {
      "word_count": 1,
      "is_palindrome": true,
      "contains_character": "a"
    }
  }
}

---

5. DELETE /strings/{string_value}

Delete a string from the system.

Response

• 204 No Content

Error Codes

• 404 – String not found

---

Setup Instructions

1. Clone the Repository

git clone https://github.com/greatm3/String-Analyzer-Service.git
cd String-Analyzer-Service

2. Install Dependencies

npm install

3. Set Environment Variables

Create a .env file in the project root:

PORT=9898
NODE_ENV=development

(Add any other variables your code uses)

4. Run Locally

npm run build # npx tsc

npm run start # node dist/index.js

API will be available at:

http://localhost:9898

Example cURL Commands

Create

curl -X POST http://localhost:9898/strings \
-H "Content-Type: application/json" \
-d '{"value": "madam"}'

Filter

curl "http://localhost:9898/strings?is_palindrome=true&min_length=3"

Natural Language

curl "http://localhost:9898/strings/filter-by-natural-language?query=strings%20containing%20the%20letter%20z"

Delete

curl -X DELETE http://localhost:9898/strings/hello

---

Tech Stack

• Language: Node.js (Express) / Typescript
• Hashing: Crypto (SHA-256)
• Hosting: Vercel

---

Author

Great Ezenna (M3)
Backend Programmer 🌐 greatm3.tech