Stack Trace Formatter
Paste code in both editors to see differences
Hint: Paste original code on left, modified code on right, then click Compare to see differences highlighted.
Hint: Paste your code, customize font size and line numbers, then click Export PDF to download formatted code.
Hint: Paste your JWT token to decode and view its header, payload, and signature. The tool validates token structure and format.
Hint: Select conversion type, paste your data, and get instant conversion. Supports JSON, YAML, XML, Excel, PDF, and more.
Issue Description
Hint: Paste any code and click Format to beautify indentation, spacing, and structure instantly.
How It Works
- Step 1: Paste raw stack trace from application logs, exception handlers, or crash reports with file paths, line numbers, and function call chains.
- Step 2: The formatter parses stack trace format identifying exception types (NullPointerException, TypeError), error messages, file locations, and call stack hierarchy.
- Step 3: Applies consistent indentation to call frames, highlights root cause (innermost exception), and organizes nested exceptions (Caused by:) for clarity.
- Step 4: Outputs formatted trace with clickable file paths, line numbers, and method names, enabling quick navigation to error source in IDEs and faster debugging.
Stack Trace Formatting Examples
Example: Java Stack Trace Formatting
java.lang.NullPointerException: Cannot invoke "String.length()" because "username" is null at com.example.UserService.validateUser(UserService.java:45) at com.example.AuthController.login(AuthController.java:23) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) Caused by: java.lang.IllegalArgumentException: Username cannot be empty at com.example.UserValidator.check(UserValidator.java:12)java.lang.NullPointerException: Cannot invoke "String.length()" because "username" is null
at com.example.UserService.validateUser(UserService.java:45)
at com.example.AuthController.login(AuthController.java:23)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
Caused by: java.lang.IllegalArgumentException: Username cannot be empty
at com.example.UserValidator.check(UserValidator.java:12)
Root Cause Analysis:
Exception Type: NullPointerException
Error Location: UserService.java:45 (validateUser method)
Trigger: Null username passed to String.length()
Call Chain:
1. AuthController.login() [line 23]
2. UserService.validateUser() [line 45] ← ERROR HERE
Underlying Issue:
IllegalArgumentException at UserValidator.check() [line 12]
Debug Steps:
✓ Check UserValidator.check() for null handling
✓ Add null check before username.length() call
✓ Validate input at AuthController levelKey Changes:
The formatter transforms single-line stack trace into hierarchical structure, making error diagnosis immediate. Each stack frame is indented with 'at' prefix, showing the call chain from entry point (AuthController.login) to error location (UserService.validateUser:45). The exception message 'Cannot invoke String.length() because username is null' pinpoints the exact failure—attempting to call a method on null reference. The 'Caused by:' section reveals the underlying IllegalArgumentException, indicating validation failure at UserValidator.check:12. This nested exception structure shows the error propagation path. File paths (UserService.java) and line numbers (45) enable IDE navigation via Ctrl+Click in IntelliJ or VS Code. The formatter highlights the root cause, separating framework code (jdk.internal.reflect) from application code. Developers use formatted traces to identify error patterns, track exception propagation, and prioritize fixes based on call frequency in production logs.
Frequently Asked Questions
What can I do with the stack trace formatter?
You can paste messy exception logs from any language and instantly reformat them with consistent spacing, indentation, and call hierarchy.
Is my stack trace uploaded to a server?
No. All processing happens in your browser, so sensitive log data never leaves your device.
Does the formatter work for all languages?
Yes. It focuses on whitespace cleanup, so Java, Python, JavaScript, Ruby, Go, and most other stack traces are supported.
Can I format very long traces?
You can paste thousands of lines. Extremely long traces may take an extra second but there are no imposed limits.
Does it modify file paths or variable values?
The formatter only touches whitespace, so file paths, messages, and line numbers stay intact for accurate debugging.