This package provides utilities for working with American Bankers Association routing transit numbers; also known as ABA RTNs.

More information about the composition, structure, and usage of ABA RTNs can be found on the relevant Wikipedia page¹.

To install as a dependency in a go project:

go get github.com/schultz-is/rtnutil

The format and checksum of an RTN can be validated via the Validate package-level function. Note that a successful result from this function does not necessarily mean that the RTN is assigned and in use!

package main

import (
  "fmt"

  "github.com/schultz-is/rtnutil"
)

func main() {
  err := rtnutil.Validate("044000037")
  if err != nil {
    panic(err)
  }

  fmt.Println("RTN is valid!")
}

In the case where an RTN is missing a check digit or one of the digits is illegible, it is possible to calculate the missing digit by replacing the missing digit with an "X" and passing it to the GetMissingDigit function. Only a single missing digit can be calculated this way, and the RTN provided must be missing exactly one digit.

package main

import (
  "fmt"

  "github.com/schultz-is/rtnutil"
)

func main() {
  missingDigit, err := rtnutil.GetMissingDigit("04400003X")
  if err != nil {
    panic(err)
  }

  fmt.Printf("the missing digit is %d", missingDigit)
}

Unit tests can be run and test coverage can be viewed via the provided Makefile.

make test
make coverage