Exhibit 10.18

Single Touch Systems, Inc.

COMMON STOCK PURCHASE AGREEMENT

This Common Stock Purchase Agreement (the “Agreement”) is made as of December 13, 2009, by and between Single Touch Systems, Inc., a Delaware corporation (the “Company”), and Mike Robert, an investor (the “Purchaser”).

AGREEMENT

NOW THEREFORE, the undersigned agree as follows:

1. Sale of Stock. Subject to the terms and conditions of this Agreement, on the Purchase Date (as defined below) the Company will issue and sell to Purchaser, and Purchaser agrees to purchase from the Company, One Million Seven Hundred Fifty Thousand (1,750,000) shares of the Company’s Common Stock (the “Shares”) at a purchase price of $0.2429 per share for a total purchase price of $425,000. The term “Shares” refers to the purchased Shares and all securities received in replacement of or in connection with the Shares pursuant to stock dividends or splits, all securities received in replacement of the Shares in a recapitalization, merger, reorganization, exchange or the like, and all new, substituted or additional securities or other properties to which Purchaser is entitled by reason of Purchaser’s ownership of the Shares.

2. Purchase. The purchase and sale of the Shares under this Agreement shall occur at the principal office of the Company simultaneously with the execution of this Agreement by the parties or on such other date as the Company and Purchaser shall agree (the “Purchase Date”).

3. Investment and Taxation Representations. In connection with the purchase of the Shares, Purchaser represents to the Company the following:

(a) Purchaser is aware of the Company’s business affairs and financial condition and has acquired sufficient information about the Company to reach an informed and knowledgeable decision to acquire the Shares. Purchaser is purchasing the Shares for investment for its own account only and not with a view to, or for resale in connection with, any “distribution” thereof within the meaning of the Securities Act.

(b) Purchaser understands that the Shares have not been registered under the Securities Act by reason of a specific exemption therefore, which exemption depends upon, among other things, the bona fide nature of Purchaser’s investment intent as expressed herein.

(c) Purchaser understands that the Shares are “restricted securities” under applicable U.S. federal and state securities laws and that, pursuant to these laws, Purchaser must hold the Shares indefinitely unless they are registered with the Securities and Exchange Commission and qualified by state authorities, or an exemption from such registration and qualification requirements is available. Purchaser acknowledges that the Company has no obligation to register or qualify the Shares for resale. Purchaser further acknowledges that if an exemption from registration or qualification is available, it may be conditioned on various requirements including, but not limited to, the time and manner of sale, the holding period for the Shares, and requirements relating to the Company which are outside of the Purchaser’s control, and which the Company is under no obligation and may not be able to satisfy.

(d) Purchaser understands that Purchaser may suffer adverse tax consequences as a result of Purchaser’s purchase or disposition of the Shares. Purchaser represents that Purchaser has consulted any tax consultants Purchaser deems advisable in connection with the purchase or disposition of the Shares and that Purchaser is not relying on the Company for any tax advice.

4. Restrictive Legends.

(a) Legends. The certificate or certificates representing the Shares shall bear the following legend (as well as any legends required by applicable state and federal corporate and securities laws):

5. Miscellaneous.

(a) Governing Law. This Agreement and all acts and transactions pursuant hereto and the rights and obligations of the parties hereto shall be governed, construed and interpreted in accordance with the laws of the State of California, without giving effect to principles of conflicts of law.

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(b) Entire Agreement; Enforcement of Rights. This Agreement sets forth the entire agreement and understanding of the parties relating to the subject matter herein and merges all prior discussions between them. No modification of or amendment to this Agreement, nor any waiver of any rights under this Agreement, shall be effective unless in writing signed by the parties to this Agreement. The failure by either party to enforce any rights under this Agreement shall not be construed as a waiver of any rights of such party.

(c) Severability. If one or more provisions of this Agreement are held to be unenforceable under applicable law, the parties agree to renegotiate such provision in good faith. In the event that the parties cannot reach a mutually agreeable and enforceable replacement for such provision, then (i) such provision shall be excluded from this Agreement, (ii) the balance of the Agreement shall be interpreted as if such provision were so excluded and (iii) the balance of the Agreement shall be enforceable in accordance with its terms.

(d) Construction. This Agreement is the result of negotiations between and has been reviewed by each of the parties hereto and their respective counsel, if any; accordingly, this Agreement shall be deemed to be the product of all of the parties hereto, and no ambiguity shall be construed in favor of or against any one of the parties hereto.

(e) Notices. Any notice required or permitted by this Agreement shall be in writing and shall be deemed sufficient when delivered personally or sent by fax or 48 hours after being deposited in the U.S. mail, as certified or registered mail, with postage prepaid, and addressed to the party to be notified at such party’s address or fax number as set forth below or as subsequently modified by written notice.

(f) Counterparts. This Agreement may be executed in two or more counterparts, each of which shall be deemed an original and all of which together shall constitute one instrument.

(g) Successors and Assigns. The rights and benefits of this Agreement shall inure to the benefit of, and be enforceable by the Company’s successors and assigns. The rights and obligations of Purchaser under this Agreement may only be assigned with the prior written consent of the Company.

(h) California Corporate Securities Law. THE SALE OF THE SECURITIES WHICH ARE THE SUBJECT OF THIS AGREEMENT HAS NOT BEEN QUALIFIED WITH THE COMMISSIONER OF CORPORATIONS OF THE STATE OF CALIFORNIA AND THE ISSUANCE OF THE SECURITIES OR THE PAYMENT OR RECEIPT OF ANY PART OF THE CONSIDERATION THEREFOR PRIOR TO THE QUALIFICATION IS UNLAWFUL, UNLESS THE SALE OF SECURITIES IS EXEMPT FROM QUALIFICATION BY SECTION 25100, 25102 OR 25105 OF THE CALIFORNIA CORPORATIONS CODE. THE RIGHTS OF ALL PARTIES TO THIS AGREEMENT ARE EXPRESSLY CONDITIONED UPON THE QUALIFICATION BEING OBTAINED, UNLESS THE SALE IS SO EXEMPT.

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The parties have executed this Agreement as of the date first set forth above.

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RECEIPT

Single Touch Systems, Inc. hereby acknowledges receipt of payment of the purchase price of $425,000 for One Million Seven Hundred Fifty Thousand (1,750,000) shares of Common Stock of Single Touch Systems, Inc.

Dated: