<PAGE>

                                                                    Exhibit 10.4

                                    SUBLEASE

This SUBLEASE entered into as of this 1st day of April 1998, by and between
Exchange Applications, Inc., with an address at 695 Atlantic Avenue, Boston, MA
02111, ("Sublessor") and Applied Language Technologies, Inc. ("Sublessee").

                                    Recitals:

A lease was made on July 9, 1996 (the "Prime Lease" attached hereto as Exhibit
"A") between Landman Omnibus V Limited Partnership ("Landman") and Grant &
Partners Limited Partnership ("Grant") for 16,114 rentable square located on the
2nd floor of the two contiguous buildings (herein, collectively the "Building"),
known respectively as 695 Atlantic Avenue and 20-24 East Street, Boston, MA. 695
Atlantic Avenue Company, L.L.C. ("Landlord") has succeeded to Landman's interest
under the Prime Lease. Grant assigned its interest in the Prime Lease to
Sublessor pursuant to an Assignment and Assumption Agreement dated November 15,
1996.

Sublessee desires to sublease from Sublessor the premises located on the 2nd
floor of the Building and containing 16,114 rentable square feet (the
"Premises") (which are shown on the plan attached hereto as Exhibit "B"), in
accordance with and subject to the terms and conditions of the Prime Lease and
this Sublease.

NOW THEREFORE, for good and valuable consideration, the receipt and adequacy of
which are hereby acknowledged, the parties hereto agree as follows:

1.    Sublease. Subject to the terms and conditions stated herein, Sublessor
      hereby subleases to Sublessee the Premises and Sublessee hereby subleases
      from the Sublessor the Premises for three (3) years and five (5) months
      commencing on June 1, 1998 ("Commencement Date") and expiring on October
      31, 2001 ("Sublease Term"). Sublessor agrees to use best efforts to vacate
      the Premises by June 1, 1998. If Sublessor has not vacated the Premises by
      June 1, 1998, the Commencement Date shall be delayed until such date as
      Sublessor vacates the Premises. If Sublessor has not vacated the Premises
      by August 1, 1998, Sublessee may terminate this Sublease by notice to
      Sublessor and upon such termination this Sublease shall become null and
      void and the parties shall have no further obligations hereunder.

2.    Consent of Landlord. Attached hereto as Exhibit C is a copy of the Consent
      of Landlord to this Sublease. In case of any conflict between the
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      provisions of the Consent and this Sublease, the provisions of the Consent
      shall prevail unaffected by the Sublease.

3.    Use. Sublessee will use the Premises of business offices and for no other
      purpose.

4.    Base Rental Payments.

           Date                      Monthly           Annually

           6/1/98 - 10/31/2001       $29,542.33        $354,508.00

      Sublessee shall pay annual rent payable in monthly installments on the
      first day of each month and such payments shall be paid by Sublessee to:

                               Exchange Applications
                               695 Atlantic Avenue
                               Boston, MA 02111

      or any such address as Sublessor may designate in writing to Sublessee. If
      the date of this Sublease is other than the first day of a month, then
      rent for such partial month shall be prorated on a per diem basis. Rent
      for the first month or partial month, as the case may be, shall be due
      upon Sublessee's execution of this Sublease, Sublessee shall pay all of
      the foregoing sums without prior demand by Sublessor or setoff by
      Sublessee except as otherwise provided herein.

      If base rent is not paid after the seventh (7th) day of the month,
      interest will accrue on such sum at the rate of 1 1/2% per month until
      such time as it is paid.

5.    Additional Rent. Base year for operating expenses shall be calendar year
      1998. Base year for taxes shall be fiscal year 1998.

      In addition to the Base rent and subject to the cap set forth below, on
      the first day of each month beginning January 1, 1999, the Sublessee shall
      pay as "Additional Rent," Sublessee's increased share of Operating
      Expenses as defined in Addendum 6 and "taxes" as defined in Article IV of
      the Prime Lease over and above the actual amounts for the calendar year
      1998 and fiscal year 1998, respectively (the Base Year) during the term
      hereof. Sublessee shall pay to the Sublessor pro rata monthly installments
      for projected Operating Expenses and taxes for the lease year beginning
      January 1, 1999, calculated by the Sublessor on the basis of the most
      recent data for Operating Expenses and taxes for actual operating
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      costs for the prior year. If the total of such monthly installment amount
      in any lease year is greater than Lessee's share of such Operating
      Expenses or taxes for such year, Sublessee shall be entitled to a credit
      against Sublessee's next due Base Rent obligations hereunder in the amount
      of such difference. If the total such monthly installment amount is less
      than Lessee's Share of such Operating Expenses or taxes for such year, the
      Sublessor shall notify Sublessee no later than 90 days after the first of
      the year and Sublessor shall pay to the Sublessee the amount of such
      difference within 30 days of receipt of a bill therefore.

6.    Utilities: Sublessee pays all electricity used at the Premises pursuant to
      the terms of Article XI of the Prime Lease.

7.    Security Deposit. Sublessee has deposited a security deposit equivalent to
      two (2) months base rent in the amount of $59,084.67 (the "Security
      Deposit") with Sublessor. Sublessor shall hold the Security Deposit as
      security for the full and faithful payment or performance by Sublessee of
      its obligations under this Sublease and not as prepayment of Rent.
      Sublessor shall not commingle the Security Deposit with other funds of
      Sublessor but shall not be liable to Sublessee for the payment of interest
      thereon or profits therefrom. Sublessor may expend such amounts from the
      Security Deposit as may be necessary to cure an Event of Default and, in
      such case, Sublessee shall pay to Sublessor the amount so expended, on
      demand. As soon as reasonably practicable after the expiration of the
      Sublease Term, Sublessor shall (i) inspect the Premises, (ii) make such
      payments from the Security Deposit as may be required to cure any
      outstanding Events of Default hereunder and (iii) if no Event of Default
      is then continuing, pay the balance of the Security Deposit to Sublessee.

8.    Condition of Premises. Sublessee acknowledges that it has inspected the
      Premises and is familiar with the physical condition thereof, and accepts
      the Premises in their "As Is" condition, except that on the Commencement
      Date, the Premises shall be delivered in clean, "broom-swept" condition
      and Sublessor shall be responsible for repairing any damage to the
      Premises caused by Sublessor's move from the Premises. Sublessee
      acknowledges that Sublessor has made no representations or warranties
      regarding the Premises, and that it has relied on no such representations
      or warranties in accepting the Premises. Sublessee acknowledges that
      Sublessor shall have no obligation to do any work in or to the Premises or
      to incur any expense in connection therewith, in order to make the
      Premises suitable and ready for occupancy and use by Sublessee. Sublessee
      shall not be responsible for the removal of any erections, additions,
      alterations or fixtures installed in the Premises by Sublessor.
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9.    Default. The occurrence of any of the following shall constitute an Event
      of Default under this Sublease:

       (i.)   Delinquency in the payment when due of Base Rent including
              Additional Rent or any other amount payable by Sublessee under
              this Sublease, or any part thereof and such failure shall continue
              for five (5) days after written notice thereof (provided, however,
              that there shall be no grace period if Sublessee has received two
              (2) written notices of payment default in the preceding 12 month
              period).

       (ii.)  Delinquency by Sublessee in the performance or compliance with any
              of the terms, covenants or agreements to be performed under this
              Sublease or the Prime Lease, and failure to rectify or remove said
              default(s) within twenty (20) days after written notice of such
              default has been received by Sublessee or, if such default shall
              reasonably require longer than twenty (20) days to cure, such
              period shall be extended for the lesser of (i) sixty (60) days or
              sooner if practicable, provided that Sublessee has commenced
              curing within such time period and thereafter diligently
              prosecutes the curing of such default, or (ii) until such a
              default becomes a default under the Prime Lease which entitles
              Landlord to terminate the Prime Lease.

       (iii.) Filing by or against Sublessee in any court pursuant to any
              federal or state statute or a petition in bankruptcy or
              insolvency, or for reorganization or rearrangement, or for the
              appointment of a receiver or trustee of all or a portion of
              Sublessee's property, or any assignment of the property of
              Sublessee for the benefit of creditors; provided, that Sublessee
              shall have sixty (60) days to obtain a dismissal of any
              involuntary proceeding.

       (iv.)  Assignment or encumbrance of this Sublease or subletting of the
              Premises other than in accordance with the terms of this Sublease.

10.   Right to Re-Enter. Upon default, after applicable notice and the
      expiration cure period, Sublessor shall have the immediate right to
      reenter and remove all persons and property within the Premises. Such
      property may be removed and stored in a public warehouse or elsewhere at
      the cost of, and for the account of Sublessee, all without service of
      notice and without Sublessor being deemed guilty of trespass, or liable
      for any loss or damage. All of the rights and remedies of Sublessor under
      this Sublease are cumulative and shall be in addition to any other rights
      or remedies accorded Sublessor by law. Sublessor shall have all rights of
      Landlord in an Event of Default as set forth in Article XV and XVII of the
      Prime Lease.
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11.   Right to Relet. Should Sublessor elect to reenter, or take possession by
      summary proceeding or other appropriate level action or proceedings, or
      pursuant to notice provided for by law, it may either terminate this
      Sublease or from time to time, without terminating this Sublease, make
      such alterations and repairs necessary to relet, and relet the Premises or
      any part thereof for such term or terms, and at such rental or rentals and
      upon such other terms and conditions as Sublessor in its sole discretion
      may deem advisable. Upon each such reletting, all rentals and other sums
      received by Sublessor shall be applied;

      (i)   to the payment of any indebtedness other than rent due;

      (ii)  to the payment of any costs and expenses of reletting, including
            brokerage and reasonable attorneys' fees, and costs of alterations
            and repairs;

      (iii) to the payment of rent and other charges due and unpaid hereunder.

12.   Assignment And Subletting. Sublessee shall not assign its rights under the
      Sublease in whole or in part or sublet all or any part of the Premises or
      assign, transfer or hypothecate by operation of law or otherwise all or
      any part of the Prime Lease or this Sublease without Sublessors' and
      Landlords' express prior written consent which consent of Sublessor shall
      not be unreasonably withheld or delayed. All of the terms and provisions
      of Article X.5 of the Prime Lease shall apply to any proposed Transfer (as
      defined in the Prime Lease), including, without limitation, the factors
      which Landlord and Sublessor may consider in determining its consent to a
      Transfer.

13.   Notices. Any notice, requests, demands and other communications between
      the parties relating to the Sublease shall be in writing and -addressed as
      follows:

                         If to Sublessor:

                         Exchange Applications
                         695 Atlantic Avenue
                         Boston, MA 02210
                         Attention: Chief Financial Officer

                         If to Sublessee:

                         Applied Language Technologies, Inc.
                         695 Atlantic Avenue
                         Boston, MA 02210
                         Attention: Chief Financial Officer
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      No notice from Sublessee to the Landlord shall be effective as to
      Sublessor unless Sublessee delivers a copy of such notice in the manner
      set forth in this section to Sublessor simultaneously with delivery of
      such notice to Landlord. No notice from Sublessee to Sublessor shall be
      effective as to Sublessor or Landlord unless Sublessee delivers a copy of
      such notice in the manner set forth in this Section to Landlord
      simultaneously with delivery of such notice to Sublessor. Any notice shall
      be deemed duly given (i) when delivered by hand, if so delivered and a
      receipt obtained, or (ii) the next day after being delivered to an
      overnight courier with acceptance signature required.

14.   Terms Subject to Prime Lease. This is a Sublease. Sublessor's interest in
      the Premises is as a tenant under the Prime Lease and Sublessee's rights
      pursuant to this Sublease are subject and subordinate at all times to the
      Prime Lease and to all the covenants and agreements of the Prime Lease,
      except as to those matters no longer applicable or superseded by this
      Sublease. The rental payments required hereunder are substituted for the
      rental payment requirements under the Prime Lease and Addendums 3, 4 and 5
      are not applicable to this Sublease and Sublessee shall not be entitled to
      any rights under Addendums 3, 4 and 5.

      Sublessee acknowledges that it has read and understands the terms and
      conditions of the Prime Lease and Sublessee expressly assumes and
      covenants to Landlord and Sublessor to keep, perform and fulfill all of
      the duties, obligations, terms and conditions which are to be kept,
      performed and fulfilled by Sublessor as tenant under the Prime Lease,
      whether or not expressly set forth in this Sublease, and agrees to be
      bound by the terms of the Prime-Lease as fully and to the same extent as
      if Sublessee were tenant under the Prime Lease. Sublessee shall not do,
      permit or tolerate anything to be done in, or in connection with
      Sublessee's use or occupancy of the Premises which would violate any
      covenant or agreement set forth in the Prime Lease. Sublessor shall have
      the same rights against Sublessee with respect to the Sublease as the
      Landlord has against the Sublessor as tenant pursuant to the Prime Lease
      and Sublessee shall have the rights and obligations of tenant of the Prime
      Lease, except where such rights and obligations are deleted, modified or
      altered herein. In addition, if Sublessor receives an abatement of rent
      under the Prime Lease, Sublessee shall also receive a pro rata abatement
      of its rent hereunder.

      If Sublessee receives from Sublessor a notice of payment default under the
      Prime Lease, Sublessee may, at its option, cure such payment default on
      behalf of Sublessor provided no default exists at such time under this
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      Sublease and that Sublessor's default is capable of being cured under the
      terms of the Prime Lease. If any such payment made by Sublessee in
      accordance with the foregoing sentence is accepted by Landlord as a cure
      of Sublessor's default, Sublessee may offset the amount of such payment
      against the next installment of rent due hereunder.

      The Landlord under the Prime Lease or Sublessor may enforce against
      Sublessee, each in its own capacity, any of the rights granted to Landlord
      pursuant to the Prime Lease, except as specifically provided in this
      Sublease. Sublessor may not grant to Sublessee, and nothing in this
      Sublease shall be construed or interpreted to grant, any greater rights
      than Sublessor has received as tenant from Landlord pursuant to the Prime
      Lease.

15.   Sublessor's Covenants. Sublessor warrants and represents that Exhibit A is
      a true, correct and accurate copy of the Prime Lease. There have been no
      modifications or amendments of or changes to the Prime Lease. The Prime
      Lease is in full force and effect and to the best of Sublessor's
      knowledge, there are no defaults or violations thereunder on the part of
      either Sublessor or Landlord.

      Sublessor shall (i) perform its obligation to pay rent under the Prime
      Lease, (ii) perform its obligations under Article 15 to deliver estoppel
      certificates and under Sections 11.1 and 11.5 to deliver certificates
      requested by Landlord or any mortgagee, (iii) not do or cause to be done
      or suffer or permit any act or thing to be done or fail to do any act
      which would or might cause a default by tenant under the Prime Lease or
      would cause the rights of Sublessor as tenant thereunder to be canceled,
      terminated or forfeited, and (iv) deliver to Sublessee as soon as possible
      -but in all events within two (2) business days of receipt, copies of any
      notices it receives from Landlord under the Prime Lease. Sublessor agrees
      not to exercise any termination rights it holds in the event of a fire or
      other casualty pursuant to Article XIV of the Prime Lease. The foregoing
      covenants of Sublessor shall survive the date of any termination of this
      Sublease resulting from a termination of the Prime Lease by Landlord after
      a default of Sublessor thereunder provided Sublessee brings a claim for
      breach within one (1) year of such termination.

16.   Limitations of Sublessor's Obligations. Sublessee hereby acknowledges that
      Sublessee will look solely to Landlord for the performance of all the
      Landlords' obligations under the Prime Lease and agrees and acknowledges
      that Sublessor shall have no obligation or responsibility whatsoever to
      provide or perform any service, repair, alteration or other similar
      obligations which is the obligations of Landlord
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      to provide or perform pursuant to the terms of the Prime Lease, provided
      however Sublessee may look to Sublessor for the prompt and proper payment
      to the Landlord of all rents received hereunder. Sublessee may exercise in
      Sublessor's name, any rights of Sublessor as tenant to enforce obligations
      of Landlord under the Prime Lease.

17.   Insurance and Indemnities. Sublessee hereby agrees to indemnify and hold
      each of Landlord and Sublessor harmless with regard to its leasing and use
      of the Premises, to the same extent that Sublessor as tenant, is required
      to indemnify and hold Landlord harmless with respect to the Premises.

      Likewise, Sublessee hereby agrees to obtain and provide evidence
      satisfactory to Sublessor, on or before the date of this Sublease, that
      Sublessee is carrying insurance in the same amounts and of the same types
      required to be carried by tenant under the Prime Lease with regard to the
      Premises. Any insurance required to be carried by Sublessee pursuant to
      the provisions of the Prime Lease shall name Landlord, Minuteman Real
      Estate Management Corporation and Spaulding and Slye Services Limited
      Partnership and Sublessor as additional insured.

18.   Sublessee's Records. Sublessee's records of operation are and shall remain
      confidential. All of Sublessee's records and files, including computerized
      records, shall be the sole property of Sublessee, and Sublessor waives any
      right to attach or lien such records and files and agrees that such
      records shall remain confidential.

19.   No Waiver. Failure of either party to complain of any act or omission on
      the part of the other party, no matter how long the same may continue,
      shall not be deemed to be a waiver by such party of any of its rights
      hereunder. No waiver by any party at any time of any other provision of
      this Sublease shall be deemed a waiver or breach of any other provision of
      this Sublease or a consent to any subsequent breach of the same or any
      other provision hereunder. If any act or omission by any party shall
      require the consent or approval of another party, such consent or approval
      of such act or omission shall not operate as consent or approval on the
      same or any subsequent occasion.

20.   Partial Invalidity. If any provision of this Sublease is held by a court
      of competent jurisdiction to be invalid, void or unenforceable in any
      manner, the remaining provisions of the Sublease shall nonetheless
      continue in full force and effect without being impaired or invalidated in
      any way. In addition, if any provision of this Sublease may be modified by
      a court of
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                                       9


      competent jurisdiction such that it may be enforced, then said provision
      shall be so modified and as modified shall be fully enforced.

21.   Corporate Authority. Sublessee warrants that the person executing this
      Sublease on behalf of Sublessee has authority to do so and fully obligate
      Sublessee to all terms and provisions of this Sublease.

22.   Governing Law. This Sublease is being executed and delivered in the
      Commonwealth of Massachusetts and the laws of that state shall govern the
      validity, construction, enforcement and interpretation of this Sublease.

23.   Entire Agreement. This Sublease contains the entire understanding of the
      parties hereto with respect to the subject matter contained herein,
      supersedes all prior and contemporaneous agreements, understandings, and
      negotiations, and no parole evidence of prior or contemporaneous
      agreements, understandings and negotiations shall govern or be used to
      construe or modify this Sublease. No modification or alteration hereof
      shall be deemed effective unless in writing and signed by the parties
      hereto.

24.   Brokerage. Sublessee represents and warrants to Sublessor that it has
      dealt solely with Whittier Partners in connection with is transaction.
      Sublessor represents and warrants to Sublessee that it has dealt with
      Whittier Partners in connection with this transaction. Sublessor shall be
      responsible for any brokerage fee owed Whittier Partners.

25.   Marginal Headings. The marginal headings hereof are inserted merely for
      the convenience of the parties and shall not be used to construe or modify
      the terms of this Sublease in any respect.

26.   Terms. Capitalized terms used in this Sublease but not defined herein
      shall have the meaning ascribed to them in the Prime Lease.

27.   Holding Over. If Sublessee remains in possession of the Premises after the
      end of this Sublease, Sublessee will occupy the Premises as a subtenant on
      a day-to-day basis at a rental rate of 200% of then current rental rate,
      subject to all conditions, provisions and obligations of this Sublease in
      effect on the last day of the term.

28.   Third Party Beneficiary. Sublessee acknowledges that the Landlord is a
      third party beneficiary entitled to receive the benefits of the
      representations, warranties and covenants made by, and the responsibility
      of, Sublessee under this Sublease.
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29.   No Renewal. Sublessee shall have no renewal options.

30.   Parties Bound. This Sublease shall be binding up and insure to the benefit
      of Sublessor and Sublessee and their respective heirs, personal
      representatives, successors and assigns.

      This SUBLEASE is executed as of the date set forth above.

                                     SUBLESSOR:

                                     Exchange Applications, Inc.

                                     By: /s/ John O'Brien
                                         ---------------------------------
                                             John O'Brien
                                     Its: VP and CFO


                                     SUBLESSEE:

                                     Applied Language Technologies, Inc.

                                     By: /s/ Arthur Haleman
                                         ---------------------------------

                                     Its: Director of Finance