Base44 Integration Development

I have an existing Base44 business command center for KXNG Cosmetics. Shopify, QuickBooks, Klaviyo, and Judge.me are already connected and working. I need an experienced Base44 developer and API integration specialist to complete stable, accurate, production-ready integrations for Amazon Seller Central, Amazon Advertising, Google Ads, and Meta Ads. This is strictly an integration project. I am not looking for a dashboard redesign, app audit, data cleanup, business strategy, or unrelated code refactoring. Do not change the existing design, calculations, pages, or working integrations except for the minimum data mapping required to populate the current app accurately. The existing Amazon connection has experienced authentication, data freshness, and reconciliation problems. I need permanent, maintainable connections that run inside my Base44 environment without manual token replacement, temporary patches, or dependency on the freelancer’s personal accounts. Required integrations Amazon Seller Central and SP-API Connect the U.S. Amazon Seller Central account using the appropriate official APIs, OAuth/LWA authorization, and secure refresh-token management. Data requirements include: Orders, ordered product sales, net sales, units, refunds, returns, cancellations, promotions, shipping, taxes, Amazon fees, settlements, and disbursements Sales by date, SKU, ASIN, parent ASIN, and product Sessions, page views, conversion rate or unit session percentage, Featured Offer/Buy Box percentage, and available Brand Analytics data FBA inventory, available units, reserved units, inbound inventory, stranded inventory, aged inventory, and replenishment-related data Seller performance and reporting data available through the authorized account Historical backfill to May 2023 where the applicable API permits it, with any API lookback limitations documented Reviews must use Amazon’s official Customer Feedback API and other compliant authorized sources. Pull available ASIN-level review topics, positive and negative themes, sentiment or topic impact, mentions, customer snippets, and month-over-month trends. Pull rating and review-count data only where officially available. Do not scrape Amazon product pages. Clearly document any review information Amazon does not expose through its APIs. Amazon Advertising must be connected separately through the Amazon Ads API. Pull applicable Sponsored Products, Sponsored Brands, and Sponsored Display data, including: Campaign, portfolio, ad group, ad, keyword, target, search term, placement, advertised ASIN, and purchased ASIN performance Spend, attributed sales, orders, units, impressions, clicks, CTR, CPC, conversion rate, ACOS, ROAS, and new-to-brand metrics where available Daily and summarized performance with the correct attribution windows TACOS calculated as Amazon ad spend divided by total Amazon sales for the same reporting period Google Ads Create a secure Google Ads API integration with proper OAuth, developer-token handling, and automatic token renewal. Pull campaign, ad group, ad, keyword, product, and Performance Max data where applicable, including: Spend, impressions, clicks, CTR, CPC, CPM, conversions, purchase conversions, conversion value, CPA, and conversion rate Platform-reported ROAS ACOS-equivalent calculated as ad spend divided by attributed purchase revenue TACOS calculated as Google ad spend divided by total Shopify revenue for the same period Attribution model, attribution window, purchase conversion action, currency, and reporting date Device, campaign type, network, and other useful reporting breakdowns supported by the current app Confirm that the correct purchase conversion actions and purchase values are being received. Do not change campaign strategy or conversion settings without approval. Meta Ads Create a secure Meta Marketing API integration with proper access-token management and automatic renewal where supported. Pull account, campaign, ad set, ad, and creative-level performance, including: Spend, impressions, reach, frequency, clicks, outbound clicks, CTR, CPC, CPM, purchases, purchase value, CPA, conversion rate, and platform-reported ROAS ACOS-equivalent calculated as ad spend divided by attributed purchase revenue TACOS calculated as Meta ad spend divided by total Shopify revenue for the same period Attribution window, conversion source, currency, and reporting date Available placement, audience, device, and campaign-objective breakdowns Validate that Meta Pixel and Conversions API reporting are sending purchase value and currency correctly. Confirm that browser and server events are deduplicated. This validation is only for ensuring accurate integration data, not for changing advertising strategy. Metric definitions and attribution The integration must keep these metrics clearly separated: Platform ROAS: platform-attributed purchase revenue divided by platform ad spend ACOS-equivalent: platform ad spend divided by platform-attributed purchase revenue TACOS: platform ad spend divided by total applicable store revenue for the same period Blended MER: total business revenue divided by combined ad spend across Amazon, Google, and Meta Do not add Google, Meta, and Amazon attributed revenue together as total business revenue. Multiple platforms can claim the same sale. Platform-attributed, channel-specific, and blended metrics must remain separately labeled. Technical requirements Use Base44 backend functions, entities, secrets, and scheduled automations wherever practical Use official, compliant APIs only Store credentials and refresh tokens securely, with no secrets hard-coded in client-side code Do not build the integrations under personal developer accounts that I will lose access to after the contract Disclose any external middleware, cloud service, subscription, or recurring cost before using it Create a Base44 version or restore point before making changes Use America/New_York as the business timezone and USD as the reporting currency Support Today, MTD, Last Month, QTD, YTD, and YoY reporting Implement scheduled synchronization near every 30 minutes where the source permits it Display the actual last successful update time and expected source-data delay Reprocess recent reporting periods so late conversions, attribution changes, refunds, and returns update automatically Use idempotent upserts and stable source IDs to prevent duplicate records Add pagination, rate-limit handling, retries with backoff, token-error handling, and useful error logs Ensure one failed integration does not prevent the other integrations from refreshing Never replace unavailable information with zero or fabricated data. Show “not connected,” “unavailable,” or “insufficient data” as appropriate Do not create duplicate calculations if the app already has the required metric logic Do not alter the working Shopify, QuickBooks, Klaviyo, or Judge.me integrations unless the change is strictly required for an approved calculation Deliverables All four production-ready API connections running inside the existing Base44 app Historical backfill using the maximum practical history available from each source Reliable scheduled refreshes and manual refresh capability Connection-health status, last-successful-sync timestamps, and actionable error reporting Written mapping of each Base44 field to its source API, endpoint, report, and metric definition Documented formulas for ROAS, ACOS-equivalent, TACOS, and blended MER Reconciliation testing against Seller Central, Amazon Ads, Google Ads, and Meta Ads for selected reporting periods Documentation covering credentials, permissions, reauthorization, sync schedules, API limitations, and future maintenance Final walkthrough and complete handoff A stated post-delivery warranty period for integration defects Acceptance requirements The project will be accepted when: Sales and advertising totals reconcile with the source dashboards after matching account, date range, timezone, currency, attribution window, order status, and metric definition Today, MTD, Last Month, QTD, YTD, and YoY filters return accurate data Scheduled refreshes run without ongoing manual intervention Tokens renew correctly or provide a clear, actionable reauthorization warning No duplicate orders, sales, campaigns, ads, or reporting records are created Source delays and API limitations are documented and displayed appropriately Existing pages and working integrations continue functioning without regression All code, credentials, data structures, and documentation are fully transferred to my Base44 environment Who should apply You must have hands-on experience building production API integrations inside Base44. General automation experience or the ability to write Base44 prompts is not enough. Your proposal must include: Examples of Base44 applications where you personally completed external API integrations Direct experience with Amazon SP-API, Amazon Ads API, Google Ads API, and Meta Marketing API Your proposed timeline, estimated hours or fixed cost, and milestone structure Any API approvals, account permissions, developer tokens, or external services you expect to need Your warranty period and terms for correcting integration defects Start your proposal with “BASE44 INTEGRATIONS” so I know you read the complete requirements.