<PAGE>

                                                                   EXHIBIT 10.15


                                 BLACKBAUD, INC.

                                SECOND AMENDMENT
                               TO CREDIT AGREEMENT

                  This SECOND AMENDMENT TO CREDIT AGREEMENT (this "AMENDMENT")
is dated as of December 19, 2000 and entered into by and among Blackbaud, Inc.,
a South Carolina corporation ("COMPANY"), the financial institutions listed on
the signature pages hereof ("LENDERS"), Bankers Trust Company, as administrative
agent for Lenders ("ADMINISTRATIVE AGENT"), Fleet Boston Corporation (formerly
known as Fleet National Bank), as documentation agent for Lenders (in such
capacity, "DOCUMENTATION AGENT"), and First Union Securities, Inc., as
syndication agent for Lenders (in such capacity, "SYNDICATION AGENT"), and is
made in reference to that certain Credit Agreement dated as of October 13, 1999,
as amended by that certain First Amendment dated as of December 6, 1999 (said
Credit Agreement as so amended being the "CREDIT AGREEMENT"), by and among
Company, Lenders, Administrative Agent, Documentation Agent and Syndication
Agent. Capitalized terms used herein without definition shall have the same
meanings herein as set forth in the Credit Agreement.

                                    RECITALS

                  WHEREAS, Company and Lenders desire to amend the Credit
Agreement (i) to amend the financial covenants as set forth herein and (ii) to
make certain other changes to the Credit Agreement, all as more specifically
provided for herein;

                  NOW, THEREFORE, in consideration of the premises and the
agreements, provisions and covenants herein contained, the parties hereto agree
as follows:

SECTION 1.        AMENDMENTS TO THE CREDIT AGREEMENT

         1.1      AMENDMENTS TO SECTION 2.4: REPAYMENTS, PREPAYMENTS AND
REDUCTIONS IN COMMITMENTS; GENERAL PROVISIONS REGARDING PAYMENTS

                  A.       Subsection 2.4B(iv)(a) is hereby amended by deleting
the last sentence contained therein in its entirety and by substituting therefor
the following:

                  "Any voluntary prepayments of the Term Loans pursuant to
                  subsection 2.4B(i) shall be applied first to reduce the
                  scheduled installments of principal of the Term Loans set
                  forth in subsection 2.4A due in the next succeeding twelve
                  months in forward order of maturity and thereafter to reduce
                  the remaining scheduled installments on a pro rata basis (in
                  accordance with the respective outstanding principal amounts
                  thereof)."

                  B.       Subsection 2.4B(iv)(c) is hereby amended by deleting
it in its entirety and by substituting therefor the following:

                  "(c). Application of Mandatory Prepayments of Term Loans by
                  Order of Maturity. Any mandatory prepayment of the Term Loans
                  pursuant to subsection

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                  2.4B(iii) shall be applied first to reduce the scheduled
                  installments of principal of the Term Loans set forth in
                  subsection 2.4A due in the next succeeding twelve months in
                  forward order of maturity and thereafter to reduce the
                  remaining scheduled installments on a pro rata basis (in
                  accordance with the respective outstanding principal amounts
                  thereof)."

         1.2      AMENDMENTS TO SECTION 7.6:  FINANCIAL COVENANTS

                  A.       Subsection 7.6A is hereby amended by deleting the
table set forth therein from the Third Fiscal Quarter 2000 through and including
the Fourth Fiscal Quarter 2002 and by substituting therefor the following:

<TABLE>
<CAPTION>
                                                               MINIMUM
          "PERIOD                                      INTEREST COVERAGE RATIO
--------------------------                             -----------------------
<S>                                                    <C>
Third Fiscal Quarter 2000                                      2.70:1.00
Fourth Fiscal Quarter 2000                                     2.25:1.00

First Fiscal Quarter 2001                                      2.25:1.00
Second Fiscal Quarter 2001                                     2.25:1.00
Third Fiscal Quarter 2001                                      2.25:1.00
Fourth Fiscal Quarter 2001                                     2.75:1.00

First Fiscal Quarter 2002                                      3.00:1.00
Second Fiscal Quarter 2002                                     3.25:1.00
Third Fiscal Quarter 2002                                      3.50:1.00
Fourth Fiscal Quarter 2002                                     3.50:1.00"
</TABLE>

                  B.       Subsection 7.6B is hereby amended by deleting the
table set forth therein from the Third Fiscal Quarter 2000 through and including
the Fourth Fiscal Quarter 2002 and by substituting therefor the following:

<TABLE>
<CAPTION>
          "PERIOD                                       MAXIMUM LEVERAGE RATIO
--------------------------                              ----------------------
<S>                                                     <C>
Third Fiscal Quarter 2000                                      3.95:1.00
Fourth Fiscal Quarter 2000                                     3.85:1.00

First Fiscal Quarter 2001                                      3.95:1.00
Second Fiscal Quarter 2001                                     4.00:1.00
Third Fiscal Quarter 2001                                      3.65:1.00
Fourth Fiscal Quarter 2001                                     3.00:1.00

First Fiscal Quarter 2002                                      2.65:1.00
Second Fiscal Quarter 2002                                     2.45:1.00
Third Fiscal Quarter 2002                                      2.20:1.00
Fourth Fiscal Quarter 2002                                     2.10:1.00"
</TABLE>

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                  C.       Subsection 7.6C is hereby amended by deleting the
table set forth therein from the Third Fiscal Quarter 2000 through and including
the Second Fiscal Quarter 2002 and by substituting therefor the following:

<TABLE>
<CAPTION>
                                                                   MINIMUM CONSOLIDATED
          "PERIOD                                                        EBITDA
          -------                                                  --------------------
<S>                                                                <C>
Third Fiscal Quarter 2000                                              $26,700,000
Fourth Fiscal Quarter 2000                                             $25,000,000

First Fiscal Quarter 2001                                              $23,000,000
Second Fiscal Quarter 2001                                             $22,500,000
Third Fiscal Quarter 2001                                              $23,000,000
Fourth Fiscal Quarter 2001                                             $26,000,000

First Fiscal Quarter 2002                                              $27,000,000
Second Fiscal Quarter 2002                                             $28,000,000"
</TABLE>

SECTION 2.        CONDITIONS TO EFFECTIVENESS

                  This Second Amendment shall become effective only upon the
satisfaction of all of the following conditions precedent (the date of
satisfaction of such conditions being referred to herein as the "SECOND
AMENDMENT EFFECTIVE DATE"):

                  A.       On or before the Second Amendment Effective Date,
Company shall deliver to Lenders (or to Administrative Agent for Lenders) the
following, each, unless otherwise noted, dated the Second Amendment Effective
Date:

                  1.       Signature and incumbency certificates of its officers
         executing this Second Amendment; and

                  2.       Copies of this Second Amendment executed by each Loan
         Party.

                  B.       Requisite Lenders shall have executed this Second

Amendment.

                  C.       On or before the Second Amendment Effective Date,
Company shall pay to Administrative Agent for distribution to each Lender
consenting to this Amendment on or prior to the Second Amendment Effective Date,
an amendment fee in an amount equal to 0.25% of the sum of such consenting
Lender's outstanding Term Loans and Revolving Loan Commitments.

                  D.       On or before the Second Amendment Effective Date, all
corporate and other proceedings taken or to be taken in connection with the
transactions contemplated hereby and all

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documents incidental thereto not previously found acceptable by Administrative
Agent, acting on behalf of Lenders, and its counsel shall be satisfactory in
form and substance to Administrative Agent and such counsel, and Administrative
Agent and such counsel shall have received all such counterpart originals or
certified copies of such documents as Administrative Agent may reasonably
request.

SECTION 3.        COMPANY'S REPRESENTATIONS AND WARRANTIES

                  In order to induce Lenders to enter into this Second Amendment
and to amend the Credit Agreement in the manner provided herein, Company
represents and warrants to each Lender that the following statements are true,
correct and complete:

                  A.       CORPORATE POWER AND AUTHORITY. Company has all
requisite corporate power and authority to enter into this Second Amendment and
to carry out the transactions contemplated by, and perform its obligations
under, the Credit Agreement as amended by this Second Amendment (the "AMENDED
AGREEMENT").

                  B.       AUTHORIZATION OF AGREEMENTS. The execution and
delivery of this Second Amendment and the performance of the Amended Agreement
have been duly authorized by all necessary corporate action on the part of
Company.

                  C.       NO CONFLICT. The execution and delivery by Company of
this Second Amendment and the performance by Company of the Amended Agreement do
not and will not (i) violate any provision of any law or any governmental rule
or regulation applicable to Company or any of its Subsidiaries, the Certificate
or Articles of Incorporation or Bylaws of Company or any of its Subsidiaries or
any order, judgment or decree of any court or other agency of government binding
on Company or any of its Subsidiaries, (ii) conflict with, result in a breach of
or constitute (with due notice or lapse of time or both) a default under any
Contractual Obligation of Company or any of its Subsidiaries, (iii) result in or
require the creation or imposition of any Lien upon any of the properties or
assets of Company or any of its Subsidiaries (other than Liens created under any
of the Loan Documents in favor of Agent on behalf of Lenders), or (iv) require
any approval of stockholders or any approval or consent of any Person under any
Contractual Obligation of Company or any of its Subsidiaries.

                  D.       GOVERNMENTAL CONSENTS. The execution and delivery by
Company of this Second Amendment and the performance by Company of the Amended
Agreement do not and will not require any registration with, consent or approval
of, or notice to, or other action to, with or by, any federal, state or other
governmental authority or regulatory body.

                  E.       BINDING OBLIGATION. This Second Amendment and the
Amended Agreement have been duly executed and delivered by Company and are the
legally valid and binding obligations of Company, enforceable against Company in
accordance with their respective terms, except as may be limited by bankruptcy,
insolvency, reorganization, moratorium or similar laws relating to or limiting
creditors' rights generally or by equitable principles relating to
enforceability.

                  F.       INCORPORATION OF REPRESENTATIONS AND WARRANTIES FROM
CREDIT AGREEMENT. The representations and warranties contained in Section 5 of
the Credit Agreement

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are and will be true, correct and complete in all material respects on and as of
the Second Amendment Effective Date to the same extent as though made on and as
of that date, except to the extent such representations and warranties
specifically relate to an earlier date, in which case they were true, correct
and complete in all material respects on and as of such earlier date.

                  G.       ABSENCE OF DEFAULT. No event has occurred and is
continuing or will result from the consummation of the transactions contemplated
by this Second Amendment that would constitute an Event of Default or a
Potential Event of Default.

SECTION 4.        MISCELLANEOUS

                  A.       REFERENCE TO AND EFFECT ON THE CREDIT AGREEMENT AND
THE OTHER LOAN DOCUMENTS.

                  (i)      On and after the Second Amendment Effective Date,
         each reference in the Credit Agreement to "this Agreement",
         "hereunder", "hereof", "herein" or words of like import referring to
         the Credit Agreement, and each reference in the other Loan Documents to
         the "Credit Agreement", "thereunder", "thereof" or words of like import
         referring to the Credit Agreement shall mean and be a reference to the
         Amended Agreement.

                  (ii)     Except as specifically amended by this Second
         Amendment, the Credit Agreement and the other Loan Documents shall
         remain in full force and effect and are hereby ratified and confirmed.

                  (iii)    The execution, delivery and performance of this
         Second Amendment shall not, except as expressly provided herein,
         constitute a waiver of any provision of, or operate as a waiver of any
         right, power or remedy of Agent or any Lender under, the Credit
         Agreement or any of the other Loan Documents.

                  B.       FEES AND EXPENSES. Company acknowledges that all
costs, fees and expenses as described in subsection 10.2 of the Credit Agreement
incurred by Agent and its counsel with respect to this Second Amendment and the
documents and transactions contemplated hereby shall be for the account of
Company.

                  C.       HEADINGS. Section and subsection headings in this
Second Amendment are included herein for convenience of reference only and shall
not constitute a part of this Second Amendment for any other purpose or be given
any substantive effect.

                  D.       APPLICABLE LAW. THIS SECOND AMENDMENT AND THE RIGHTS
AND OBLIGATIONS OF THE PARTIES HEREUNDER SHALL BE GOVERNED BY, AND SHALL BE
CONSTRUED AND ENFORCED IN ACCORDANCE WITH, THE INTERNAL LAWS OF THE STATE OF NEW
YORK (INCLUDING WITHOUT LIMITATION SECTION 5-1401 OF THE GENERAL OBLIGATIONS LAW
OF THE STATE OF NEW YORK), WITHOUT REGARD TO CONFLICTS OF LAWS PRINCIPLES.

                  E.       COUNTERPARTS. This Second Amendment may be executed
in any number of counterparts and by different parties hereto in separate
counterparts, each of which when so

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executed and delivered shall be deemed an original, but all such counterparts
together shall constitute but one and the same instrument; signature pages may
be detached from multiple separate counterparts and attached to a single
counterpart so that all signature pages are physically attached to the same
document.

                  [Remainder of page intentionally left blank]

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                  IN WITNESS WHEREOF, the parties hereto have caused this Second
Amendment to be duly executed and delivered by their respective officers
thereunto duly authorized as of the date first written above.

                                       BLACKBAUD, INC.

                                       By:    /s/ Robert Sywolski
                                              --------------------------------
                                       Title: CEO, President

                                      S-1
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                                       LENDERS:

                                       BANKERS TRUST COMPANY,
                                       as Administrative Agent and as a Lender

                                       By:    /s/ Mary Jo Jolly
                                              ----------------------------------
                                       Title: Assistant Vice President

                                      S-2
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                                       FLEET BOSTON CORPORATION,
                                       as Documentation Agent and as a Lender

                                       By:    /s/ signature illegible
                                              ----------------------------------
                                       Title: ________________________________

                                      S-3
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                                       FIRST UNION SECURITIES, INC.,
                                       as Syndication Agent

                                       By:    /s/ signature illegible
                                              --------------------------------
                                       Title: V.P.

                                      S-4
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                                       FIRST UNION NATIONAL BANK,
                                       as a Lender

                                       By:    /s/ signature illegible
                                              ----------------------------------
                                       Title: V.P.

                                      S-5
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                                       BANK AUSTRIA CREDITANSTALT
                                       CORPORATE FINANCE, as a LENDER

                                       By:    /s/ Stanley M. Guralnik
                                              ----------------------------------
                                       Title: Vice President

                                       By:    /s/ signature illegible
                                              ----------------------------------
                                       Title: VP

                                      S-6
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                                       FIRST SOURCE FINANCIAL, LLP,
                                       as a Lender

                                       By:    First Source Financial, Inc.,
                                              its Agent/Manager

                                       By:    /s/ signature illegible
                                              ----------------------------------
                                       Title: Senior Vice President

                                      S-7
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                                       HELLER FINANCIAL, INC.,
                                       as a Lender

                                       By:    /s/ signature illegible
                                              ----------------------------------
                                       Title: Vice President

                                      S-8
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                                       FIRST DOMINION CAPITAL,
                                       as a Lender

                                       By:    /s/ signature illegible
                                              ----------------------------------
                                       Title: __________________________________

                                      S-9