17. Non-transitory computer storage comprising instructions for causing a computer system to group documents by a process that comprises: receiving a first document and a second document, wherein each of the first document and the second document comprises distinct character types; generating a first indicator of a common character count between the first document and the second document, wherein the common character count corresponds to a number of distinct character type occurrences in both the first document and the second document; generating a second indicator of a character variance count between the first document and the second document, wherein the character variance count corresponds to differences in a number of occurrences of distinct character types in both the first document and the second document; generating a third indicator of a missing character count between the first document and the second document, wherein the missing character count corresponds to a number of distinct character type occurrences in the first document and not in the second document; generating a single indicator by combining at least the first indicator, the second indicator, and the third indicator; comparing the single indicator to a threshold indicator to determine whether there is a match between the first document and the second document; and transmitting matching information indicative of the comparison of the single indicator to the threshold indicator over a network to a computing device.
17. Non-transitory computer storage comprising instructions for causing a computer system to group documents by a process that comprises: receiving a first document and a second document, wherein each of the first document and the second document comprises distinct character types; generating a first indicator of a common character count between the first document and the second document, wherein the common character count corresponds to a number of distinct character type occurrences in both the first document and the second document; generating a second indicator of a character variance count between the first document and the second document, wherein the character variance count corresponds to differences in a number of occurrences of distinct character types in both the first document and the second document; generating a third indicator of a missing character count between the first document and the second document, wherein the missing character count corresponds to a number of distinct character type occurrences in the first document and not in the second document; generating a single indicator by combining at least the first indicator, the second indicator, and the third indicator; comparing the single indicator to a threshold indicator to determine whether there is a match between the first document and the second document; and transmitting matching information indicative of the comparison of the single indicator to the threshold indicator over a network to a computing device. 20. The non-transitory computer storage of claim 17 , further comprising instructions for causing the computer system to group documents by: generating an index based on one or more document features, wherein the index is stored in a second non-transitory computer storage.