Ediff was written by Michael Kifer <kifer@cs.stonybrook.edu>. It was inspired by emerge.el written by Dale R. Worley <drw@math.mit.edu>. An idea due to Boris Goldowsky <boris@cs.rochester.edu> made it possible to highlight fine differences in Ediff buffers. Alastair Burt <burt@dfki.uni-kl.de> ported Ediff to XEmacs, Eric Freudenthal <freudent@jan.ultra.nyu.edu> made it work with VC, Marc Paquette <marcpa@cam.org> wrote the toolbar support package for Ediff, and Hrvoje Nikšić <hniksic@xemacs.org> adapted it to the Emacs customization package.
Many people provided help with bug reports, feature suggestions, and advice. Without them, Ediff would not be nearly as useful as it is today. Here is a hopefully full list of contributors:
Adrian Aichner (aichner at ecf.teradyne.com), Drew Adams (drew.adams at oracle.com), Steve Baur (steve at xemacs.org), Neal Becker (neal at ctd.comsat.com), E. Jay Berkenbilt (ejb at ql.org), Lennart Borgman (ennart.borgman at gmail.com) Alastair Burt (burt at dfki.uni-kl.de), Paul Bibilo (peb at delcam.co.uk), Kevin Broadey (KevinB at bartley.demon.co.uk), Harald Boegeholz (hwb at machnix.mathematik.uni-stuttgart.de), Bradley A. Bosch (brad at lachman.com), Michael D. Carney (carney at ltx-tr.com), Jin S. Choi (jin at atype.com), Scott Cummings (cummings at adc.com), Albert Dvornik (bert at mit.edu), Eric Eide (eeide at asylum.cs.utah.edu), Paul Eggert (eggert at twinsun.com), Urban Engberg (ue at cci.dk), Kevin Esler (esler at ch.hp.com), Robert Estes (estes at ece.ucdavis.edu), Jay Finger (jayf at microsoft.com), Xavier Fornari (xavier at europe.cma.fr), Eric Freudenthal (freudent at jan.ultra.nyu.edu), Job Ganzevoort (Job.Ganzevoort at cwi.nl), Felix Heinrich Gatzemeier (felix.g at tzemeier.info), Boris Goldowsky (boris at cs.rochester.edu), Allan Gottlieb (gottlieb at allan.ultra.nyu.edu), Aaron Gross (aaron at bfr.co.il), Thorbjoern Hansen (thorbjoern.hansen at mchp.siemens.de), Marcus Harnisch (marcus_harnisch at mint-tech.com), Steven E. Harris (seh at panix.com), Aaron S. Hawley (Aaron.Hawley at uvm.edu), Xiaoli Huang (hxl at epic.com), Andreas Jaeger (aj at suse.de), Lars Magne Ingebrigtsen (larsi at ifi.uio.no), Larry Gouge (larry at itginc.com), Karl Heuer (kwzh at gnu.org), (irvine at lks.csi.com), (jaffe at chipmunk.cita.utoronto.ca), David Karr (dkarr at nmo.gtegsc.com), Norbert Kiesel (norbert at i3.informatik.rwth-aachen.de), Steffen Kilb (skilb at gmx.net), Leigh L Klotz (klotz at adoc.xerox.com), Fritz Knabe (Fritz.Knabe at ecrc.de), Heinz Knutzen (hk at informatik.uni-kiel.d400.de), Andrew Koenig (ark at research.att.com), Hannu Koivisto (azure at iki.fi), Ken Laprade (laprade at dw3f.ess.harris.com), Will C Lauer (wcl at cadre.com), Richard Levitte (levitte at e.kth.se), Mike Long (mike.long at analog.com), Dave Love (d.love at dl.ac.uk), Martin Maechler (maechler at stat.math.ethz.ch), Simon Marshall (simon at gnu.org), Paul C. Meuse (pmeuse at delcomsys.com), Richard Mlynarik (mly at adoc.xerox.com), Stefan Monnier (monnier at cs.yale.edu), Chris Murphy (murphycm at sun.aston.ac.uk), Erik Naggum (erik at naggum.no), Eyvind Ness (Eyvind.Ness at hrp.no), Ray Nickson (nickson at cs.uq.oz.au), Dan Nicolaescu (dann at ics.uci.edu), David Petchey (petchey_david at jpmorgan.com), Benjamin Pierce (benjamin.pierce at cl.cam.ac.uk), François Pinard (pinard at iro.umontreal.ca), Tibor Polgar (tlp00 at spg.amdahl.com), David Prince (dave0d at fegs.co.uk), Paul Raines (raines at slac.stanford.edu), Stefan Reicher (xsteve at riic.at), Charles Rich (rich at merl.com), Bill Richter (richter at math.nwu.edu), C.S. Roberson (roberson at aur.alcatel.com), Kevin Rodgers (kevin.rodgers at ihs.com), Sandy Rutherford (sandy at ibm550.sissa.it), Heribert Schuetz (schuetz at ecrc.de), Andy Scott (ascott at pcocd2.intel.com), Axel Seibert (axel at tumbolia.ppp.informatik.uni-muenchen.de), Vin Shelton (acs at xemacs.org), Scott O. Sherman (Scott.Sherman at mci.com), Nikolaj Schumacher (n_schumacher at web.de), Richard Stallman (rms at gnu.org), Richard Stanton (stanton at haas.berkeley.edu), Sam Steingold (sds at goems.com), Ake Stenhoff (etxaksf at aom.ericsson.se), Stig (stig at hackvan.com), Peter Stout (Peter_Stout at cs.cmu.edu), Chuck Thompson (cthomp at cs.uiuc.edu), Ray Tomlinson (tomlinso at bbn.com), Raymond Toy (toy at rtp.ericsson.se), Stephen J. Turnbull (stephen at xemacs.org), Jan Vroonhof (vroonhof at math.ethz.ch), Colin Walters (walters at cis.ohio-state.edu), Philippe Waroquiers (philippe.waroquiers at eurocontrol.be), Klaus Weber (gizmo at zork.north.de), Ben Wing (ben at xemacs.org), Tom Wurgler (twurgler at goodyear.com), Steve Youngs (youngs at xemacs.org), Ilya Zakharevich (ilya at math.ohio-state.edu), Eli Zaretskii (eliz at is.elta.co.il)