Approximate string matching of a target string to a trie data structure in which the trie data structure has a root node and generations of child nodes, each node representing at least one character in an alphabet to provide a lexicon of words and word fragments. Traversing the trie data structure includes starting from the root node by comparing each node of a branch of the trie data structure to characters in the target string and adding characters traversed in a branch of the trie data structure to a gathered string to provide suggestions of approximate matches. If a node is reached that is flagged as a node for a word or a word fragment and, and if the target string is longer than the gathered string, the method loops back to the root node, and continues the traverse from the root node. At each node, the system determines if there is a correction rule for one or more characters in the remainder of the target string from the current node, and if so, applies the correction rule to the target string to obtain a modified target string.