DEV Community

Cover image for I Built 404ping — A Lightweight API Testing CLI (curl + Postman had a baby)
Nimesh Thakur
Nimesh Thakur

Posted on

I Built 404ping — A Lightweight API Testing CLI (curl + Postman had a baby)

#linux #webdev #javascript #programming

The Problem

Picture this: It's 2 AM. You're deep in API testing. You've got 15 endpoints to test, each with auth tokens, custom headers, and JSON bodies.

Option 1: Postman

  • Open Postman... loading... still loading
  • Internet hiccups? Request failed.
  • Crashes randomly. Lost your work.
  • 500MB+ of RAM just sitting there.

Option 2: curl

curl -X POST https://api.example.com/auth/login \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..." \
  -d '{"email":"test@example.com","password":"secret123"}'
Enter fullscreen mode Exit fullscreen mode

Every. Single. Time. No memory. No variables. Copy-paste hell.

I was tired. So I built something better.

Introducing 404ping 🚀

Lightweight API testing CLI — curl with a brain.

# What used to be this nightmare...
curl -X POST https://api.myapp.com/auth/login \
  -H "Authorization: Bearer abc123" \
  -d '{"email":"test@test.com"}'

# Becomes this...
404ping run myapp:login
Enter fullscreen mode Exit fullscreen mode

That's it. One command. Done.

Installation 

# Clone it
git clone https://github.com/toklas495/404ping.git
cd 404ping

# Install & build
npm install
npm run build

# Now use it anywhere
404ping
Enter fullscreen mode Exit fullscreen mode

You'll see this beautiful banner:

   _  _    ___  _  _         _             
  | || |  / _ \| || |       (_)            
  | || |_| | | | || |_ _ __  _ _ __   __ _ 
  |__   _| | | |__   _| '_ \| | '_ \ / _` |
     | | | |_| |  | | | |_) | | | | | (_| |
     |_|  \___/   |_| | .__/|_|_| |_|\__, |
                      | |             __/ |
                      |_|            |___/
Enter fullscreen mode Exit fullscreen mode

Core Features

1️⃣ Simple Requests

Just like curl, but cleaner:

# GET request
404ping request https://api.example.com/users

# POST with JSON body
404ping request https://api.example.com/login \
  -X POST \
  -d '{"email":"test@example.com","password":"secret"}'

# With headers
404ping request https://api.example.com/me \
  -H "Authorization: Bearer mytoken"
Enter fullscreen mode Exit fullscreen mode

2️⃣ Global Variables (Game Changer)

Set once, use everywhere with {{variable}} syntax:

# Set variables globally
404ping set host:https://api.myapp.com token:abc123 -g

# Now use them in any request
404ping request {{host}}/users/me -H "Authorization: Bearer {{token}}"
Enter fullscreen mode Exit fullscreen mode

Why this matters:

  • Token expired? Update once: 404ping set token:newtoken -g
  • Testing staging? Change once: 404ping set host:https://staging.myapp.com -g
  • No more find-and-replace across 50 requests. 
# List all variables
404ping vars

# Remove variables
404ping unset host token
Enter fullscreen mode Exit fullscreen mode

3️⃣ Collections (Save Your Sanity)

Group related requests together:

# Create a collection
404ping collection create myapp

# Save requests to it
404ping collection save myapp login \
  -X POST {{host}}/auth/login \
  -d '{"email":"{{email}}","password":"{{pass}}"}'

404ping collection save myapp get-profile \
  {{host}}/users/me \
  -H "Authorization: Bearer {{token}}"

404ping collection save myapp update-user \
  -X PUT {{host}}/users/me \
  -d '{"name":"New Name"}' \
  -H "Authorization: Bearer {{token}}"

# List all collections
404ping collection list

# See requests in a collection
404ping collection show myapp
Enter fullscreen mode Exit fullscreen mode

4️⃣ Run Saved Requests (The Magic)

This is where 404ping shines:

# Run any saved request instantly
404ping run myapp:login
404ping run myapp:get-profile
404ping run myapp:update-user
Enter fullscreen mode Exit fullscreen mode

Override without saving:

# Test with different URL (temporary)
404ping run myapp:login -u "https://staging.api.com/auth/login"

# Test with different body (temporary)
404ping run myapp:login -d '{"email":"other@test.com","password":"test"}'
Enter fullscreen mode Exit fullscreen mode

Override AND save:

# Permanently update the saved request
404ping run myapp:login -u "https://newapi.com/auth/login" --save
Enter fullscreen mode Exit fullscreen mode

5️⃣ Collection-Scoped Variables

Use variables from specific collections:

# Reference collection variables
404ping request {{myapp.host}}/api/v1/users
404ping request {{another-project.host}}/api/endpoint
Enter fullscreen mode Exit fullscreen mode

Output Options 

# Show response headers
404ping request {{host}}/api/users -i

# Show response size
404ping request {{host}}/api/users --size

# Raw output (pipe to jq, files, etc.)
404ping request {{host}}/api/users --raw

# Request summary
404ping request {{host}}/api/users --info

# Full debug dump
404ping request {{host}}/api/users --debug
Enter fullscreen mode Exit fullscreen mode

Real-World Workflow

Here's how I use 404ping daily:

# 1. Setup environment
404ping set host:https://api.target.com -g

# 2. Create project collection
404ping collection create target-app

# 3. Save auth request
404ping collection save target-app login \
  -X POST {{host}}/auth/login \
  -d '{"email":"test@test.com","password":"password123"}'

# 4. Test login
404ping run target-app:login

# 5. Got token? Save it!
404ping set token:eyJhbGciOiJIUzI1NiIs... -g

# 6. Save authenticated endpoints
404ping collection save target-app profile \
  {{host}}/users/me \
  -H "Authorization: Bearer {{token}}"

404ping collection save target-app admin-panel \
  {{host}}/admin/dashboard \
  -H "Authorization: Bearer {{token}}"

# 7. Test everything quickly
404ping run target-app:profile
404ping run target-app:admin-panel

# 8. Found IDOR? Test with different IDs
404ping run target-app:profile -u "{{host}}/users/123"
404ping run target-app:profile -u "{{host}}/users/456"
Enter fullscreen mode Exit fullscreen mode

Why I Built This

I'm a bug bounty hunter. I test APIs all day.

Postman problems:

  • Heavy (500MB+ RAM)
  • Needs internet for sync
  • Crashes on my potato laptop
  • Slow startup

curl problems:

  • No memory (copy-paste everything)
  • No variables
  • Long commands for simple requests
  • Easy to make typos

404ping solution:

  • Lightweight (~50MB)
  • Works offline
  • Variables like Postman
  • Fast like curl
  • Collections for organization
  • Runs saved requests instantly

Command Cheatsheet

Command Description
404ping request <url> Send HTTP request
404ping set <key:value> -g Set global variable
404ping unset <keys> Remove variables
404ping vars List all variables
404ping collection create <name> Create collection
404ping collection save <coll> <req> Save request
404ping collection list List collections
404ping collection show <name> Show collection requests
404ping run <coll:req> Run saved request
404ping run <coll:req> --save Run & save changes

Options Reference

Option Alias Description
--method -X HTTP method (GET/POST/PUT/DELETE)
--data -d JSON request body
--header -H Custom header (repeatable)
--url -u Override URL (in run command)
--s_header -i Show response headers
--size Show response size
--raw Raw output
--info Request summary
--debug Full dump
--save Save overrides permanently
--global -g Save variable globally

What's Next?

Planning to add:

  • [ ] Environment files (.env support)
  • [ ] Request chaining (use response in next request)
  • [ ] Export to curl command
  • [ ] Import from Postman collections
  • [ ] Response assertions

Try It Out! 

git clone https://github.com/toklas495/404ping.git
cd 404ping
npm install && npm run build
404ping --help
Enter fullscreen mode Exit fullscreen mode

GitHub: github.com/toklas495/404ping

Final Thoughts

I built 404ping because I needed it. No fancy UI, no cloud sync, no subscription — just a fast CLI that remembers my requests.

If you're a bug bounty hunter, API developer, or anyone who tests APIs from terminal — give it a shot.

Found a bug? Have a feature request? Open an issue or PR. Let's build this together.

Happy hunting! 🎯

— Nimesh (toklas495)

If this helped you, drop a ❤️ and follow for more tools & writeups!

Top comments (0)