diff --git a/src/bin/checksum.rs b/src/bin/checksum.rs
new file mode 100644
index 0000000..dd02b08
--- /dev/null
+++ b/src/bin/checksum.rs
@@ -0,0 +1,164 @@
+//! This is a simple program to calculate a checksum from the command line
+
+use crc_fast::{checksum, checksum_file, CrcAlgorithm};
+use std::env;
+use std::process::ExitCode;
+use std::str::FromStr;
+
+#[derive(Debug)]
+struct Config {
+    algorithm: String,
+    file: Option<String>,
+    string: Option<String>,
+    format: OutputFormat,
+}
+
+#[derive(Debug, Clone)]
+enum OutputFormat {
+    Hex,
+    Decimal,
+}
+
+fn print_usage() {
+    println!("Usage: checksum -a algorithm [-f file] [-s string] [--format hex|decimal]");
+    println!();
+    println!("Example: checksum -a CRC-32/ISCSI -f myfile.txt");
+    println!("Example: checksum -a CRC-64/NVME -s 'Hello, world!' --format decimal");
+    println!();
+    println!("Options:");
+    println!("  -a algorithm        Specify the checksum algorithm (required)");
+    println!("  -f file             Calculate checksum for the specified file");
+    println!("  -s string           Calculate checksum for the specified string");
+    println!("  --format hex|decimal Output format (default: hex)");
+    println!("  -h, --help          Show this help message");
+    println!();
+    println!("Note: Either -f or -s must be provided, but not both.");
+}
+
+fn parse_args() -> Result<Config, String> {
+    let args: Vec<String> = env::args().collect();
+
+    if args.len() == 1 {
+        return Err("No arguments provided".to_string());
+    }
+
+    // Check for help flag
+    if args.contains(&"-h".to_string()) || args.contains(&"--help".to_string()) {
+        return Err("help".to_string());
+    }
+
+    let mut algorithm: Option<String> = None;
+    let mut file: Option<String> = None;
+    let mut string: Option<String> = None;
+    let mut format = OutputFormat::Hex; // Default to hex
+
+    let mut i = 1; // Skip program name
+    while i < args.len() {
+        match args[i].as_str() {
+            "-a" => {
+                if i + 1 >= args.len() {
+                    return Err("Missing algorithm after -a flag".to_string());
+                }
+                algorithm = Some(args[i + 1].clone());
+                i += 2;
+            }
+            "-f" => {
+                if i + 1 >= args.len() {
+                    return Err("Missing filename after -f flag".to_string());
+                }
+                if string.is_some() {
+                    return Err("Cannot specify both -f and -s flags".to_string());
+                }
+                file = Some(args[i + 1].clone());
+                i += 2;
+            }
+            "-s" => {
+                if i + 1 >= args.len() {
+                    return Err("Missing string after -s flag".to_string());
+                }
+                if file.is_some() {
+                    return Err("Cannot specify both -f and -s flags".to_string());
+                }
+                string = Some(args[i + 1].clone());
+                i += 2;
+            }
+            "--format" => {
+                if i + 1 >= args.len() {
+                    return Err("Missing format after --format flag".to_string());
+                }
+                match args[i + 1].as_str() {
+                    "hex" => format = OutputFormat::Hex,
+                    "decimal" => format = OutputFormat::Decimal,
+                    invalid => {
+                        return Err(format!(
+                            "Invalid format '{}'. Use 'hex' or 'decimal'",
+                            invalid
+                        ))
+                    }
+                }
+                i += 2;
+            }
+            arg => {
+                return Err(format!("Unknown argument: {}", arg));
+            }
+        }
+    }
+
+    // Validate required arguments
+    let algorithm = algorithm.ok_or("Algorithm (-a) is required")?;
+
+    if file.is_none() && string.is_none() {
+        return Err("Either -f (file) or -s (string) must be provided".to_string());
+    }
+
+    Ok(Config {
+        algorithm,
+        file,
+        string,
+        format,
+    })
+}
+
+fn calculate_checksum(config: &Config) -> Result<(), String> {
+    let algorithm = CrcAlgorithm::from_str(&config.algorithm)
+        .map_err(|_| format!("Invalid algorithm: {}", config.algorithm))?;
+
+    let checksum = if let Some(ref filename) = config.file {
+        checksum_file(algorithm, filename, None).unwrap()
+    } else if let Some(ref text) = config.string {
+        checksum(algorithm, text.as_bytes())
+    } else {
+        return Err("No input provided for checksum calculation".to_string());
+    };
+
+    match config.format {
+        OutputFormat::Hex => println!("{:#x?}", checksum),
+        OutputFormat::Decimal => println!("{}", checksum),
+    }
+
+    Ok(())
+}
+
+fn main() -> ExitCode {
+    match parse_args() {
+        Ok(config) => {
+            if let Err(e) = calculate_checksum(&config) {
+                eprintln!("Error: {}", e);
+                return ExitCode::from(1);
+            }
+        }
+        Err(msg) => {
+            if msg == "help" {
+                print_usage();
+                return ExitCode::SUCCESS;
+            } else {
+                eprintln!("Error: {}", msg);
+                println!();
+                print_usage();
+                return ExitCode::from(1);
+            }
+        }
+    }
+
+    ExitCode::SUCCESS
+}