Method of Exporting Umbraco dictionary items to Excel and back. Uses http://epplus.codeplex.com. Based on https://github.com/hfloyd/DictionaryDashboardForUmbraco

DictionaryExport.ashx

<%@ WebHandler Language="C#" Class="DictionaryExport" %>

using System;
using System.IO;
using System.Web;
using System.Collections.Generic;
using System.Linq;


using umbraco.cms.businesslogic;
using umbraco.cms.businesslogic.language;

public class DictionaryExport : IHttpHandler {

	protected List<Language> allLanguages = new List<Language>();
	
    public void ProcessRequest (HttpContext context) {
        
		allLanguages.AddRange(Language.GetAllAsList());
		
		var list = new List<Dictionary.DictionaryItem>();		
		foreach (var root in Dictionary.getTopMostItems) {			
			this.AddToList(root, ref list);
		}		
		
		var excel = new OfficeOpenXml.ExcelPackage();
		var sheet = excel.Workbook.Worksheets.Add("Dictionary");
		sheet.DefaultColWidth = 30;


		sheet.Cells["A1"].Value = "Key";
		sheet.Cells["B1"].Value = "Description";
		
		int col = 3;
		int row = 1;
		foreach (var lang in allLanguages) {
			sheet.Cells[1, col].Value = lang.CultureAlias;
			col++;
		}
		sheet.Cells["1:1"].Style.Font.Bold = true;
		sheet.Cells["1:1"].Style.Font.Size = 12;
		
		row = 2;
		foreach (var item in list) {
			sheet.Row(row).Hidden = String.IsNullOrWhiteSpace(item.Value(allLanguages.First().id));
			sheet.Cells[row, 1].Value = item.key;
			col = 3;
			foreach (var lang in allLanguages) {
				sheet.Cells[row, col].Value = item.Value(lang.id).Replace("\n", ">");
				col++;
			}
			row++;			
		}	
		

		context.Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
		context.Response.AddHeader("content-disposition", "attachment;  filename=Dictionary.xlsx");
		context.Response.BinaryWrite(excel.GetAsByteArray());

		
    }
	
	private void AddToList ( Dictionary.DictionaryItem parent, ref List<Dictionary.DictionaryItem> list ) {
		list.Add(parent);
		if (parent.hasChildren) {
			foreach (var item in parent.Children) {
				AddToList(item, ref list);
			}
		}		
	}


 
    public bool IsReusable {
        get {
            return false;
        }
    }

}

DictionaryImport.ashx

<%@ WebHandler Language="C#" Class="DictionaryImport" %>

using System;
using System.Collections.Generic;

using System.Web;
using System.IO;
using System.Linq;

using umbraco.cms.businesslogic;
using umbraco.cms.businesslogic.language;


public class DictionaryImport : IHttpHandler {

	protected List<Language> allLanguages = new List<Language>();
	
    	public void ProcessRequest (HttpContext context) {
        	context.Response.ContentType = "text/plain";
        	
		allLanguages.AddRange(Language.GetAllAsList());
		
		FileInfo file = new FileInfo(context.Server.MapPath("~/App_Data/Dictionary.xlsx"));
		var excel = new OfficeOpenXml.ExcelPackage(file);
		var sheet = excel.Workbook.Worksheets.First();
				
		foreach (var key in sheet.Cells["A:A"]) {
			if (!Dictionary.DictionaryItem.hasKey(key.Value.ToString())) {
				context.Response.Write("NO KEY:" + key.Value.ToString() + "\n");
				continue;
			}
			var dictItem = new Dictionary.DictionaryItem(key.Value.ToString());
			foreach (var cell in sheet.Cells[key.Start.Row.ToString() + ":" + key.Start.Row.ToString()].Skip(1)) {
				if (allLanguages.Any(x => x.CultureAlias.ToLower() == sheet.Cells[cell.Address.Substring(0, 1) + "1"].Value.ToString())) {
					var lang = allLanguages.First(x => x.CultureAlias.ToLower() == sheet.Cells[cell.Start.Address.Substring(0, 1) + "1"].Value.ToString());
					context.Response.Write(dictItem.key + "-" + lang.CultureAlias + ":" + cell.Value + "\n");
					dictItem.setValue(lang.id, cell.Value.ToString().Replace(">", "\n").Trim());
				}
				
			}
	}
	excel.Dispose();
    }
    public bool IsReusable {
        get {
            return false;
        }
    }
}