Best Unified API for CRM in 2026

For CRM, the unified API to choose depends on what you need to write back and how the objects are designed. Unified.to and Apideck are both pass-through, so caching does not separate them. Unified.to publishes read, write, and change-event coverage across 212 CRM integrations (most accept writes; support varies by integration) and embeds related records in one object. Merge fits teams that want a stored copy, logs and issue detection on every plan, or ISO 27001. Apideck fits an embedded integrations marketplace, and Nango fits teams that want to write their own integration code.

What is the best unified API for CRM in 2026?

The best unified API for CRM is the one whose write depth and object model match your product: Unified.to for bidirectional sync with per-CRM write depth published, Merge for a stored copy with observability on every plan, Apideck for an embedded marketplace, and Nango for code-first control. Each has limits worth knowing before you build.

Why does CRM write support matter more than integration count?

Reading a contact is trivial. Creating one against five different validation models is where unified APIs diverge, and most are stronger at reads than writes. Unified.to publishes write support across 6 objects (Company, Contact, Deal, Event, Lead, Pipeline), and most of its CRM integrations accept writes, named rather than asserted. Support varies by integration, so check each integration's Feature Support tab in the docs.

Some integrations are read-only today, including Bunny.com, CalendarHero, DealCloud, Marketing360, Modjo, and Rev Sport: they return data but do not accept writes through the unified model. Naming them is the point, so a developer planning a write path knows which are out before they build, not after. Coverage is built from customer requests, so if you need writes on one of these, you can request it and move it up the roadmap.

How is Unified.to's CRM object model different from Merge's and Apideck's?

Unified.to embeds related CRM data inside parent objects, so one call returns an enriched record: one Event object carries nine activity types, and Deal, Contact, and Company each hold the others' ID arrays. Merge and Apideck model more of that data as separate objects.

• Activities: Unified.to's Event carries note, meeting, email, call, task, marketing_email, form, page_view, and its record type in a single object. HubSpot's own API puts those behind a separate Engagements endpoint per type.
• Merge: Merge models engagement types and association types as their own objects, and its expand parameter can return them in the same call. Unified.to carries the type on the Event record.
• Apideck: Apideck's CRM API lists eleven named resources, and its per-connector coverage tracks Notes and Activities as separate objects that overlap, since an Activity can itself be a note. Apideck's writes are strong: it accepts writes on contacts across twenty of its twenty-one CRM connectors.
• Picklists: Unified.to's Picklist is a list-only endpoint that returns field option sets directly, on every plan.

The trade-off is assembly work. The more first-class objects a model has, the more you fetch and stitch together for one enriched record, unless the API returns related objects in the same call, as Merge's expand does.

Which CRMs does each platform actually support, and how deeply?

Unified.to supports 212 CRM integrations, Merge 21 (2 October 2026) and Apideck 21 with contacts coverage (8 October 2026). Nango's unified API page lists 94 CRMs (8 October 2026), where "supported" means auth, proxy and logs and you write the syncs. Counts hide depth, so Unified.to publishes read, write, and change-event support per integration. Across the five CRMs most buyers test first: HubSpot at 98 readable and 56 writable properties, Salesforce at 87 and 40, Pipedrive at 83 and 40, Zoho at 78 and 35, and Dynamics 365 Sales at 74 and 40 (July 2026).

How do you keep CRM data current: sync, pass-through, or webhooks?

Merge stores a synced copy and advises polling every 24 hours as a safety net. Unified.to and Apideck hit the source live on every call, so a read reflects current state. For change detection, Unified.to forwards native events where the CRM sends them, as on HubSpot, Pipedrive and Attio, and runs virtual webhooks on most other CRM integrations, including Salesforce and Zoho CRM.

One limit deserves stating rather than burying. Deletion events are thin across CRM sources: only a few integrations emit contact-deleted or deal-deleted events, and fewer emit event-deleted. Creation and update coverage is broad, but if your product depends on detecting deletions, verify that the specific CRM you need emits the event before you design around it. Where a CRM sends no native event, Unified.to's virtual webhooks detect changes at a configurable interval, as frequent as every minute on paid plans. Some integrations list no CRM change events at all, native or virtual, as of 1 October 2026, including Google Contacts, Monday, Zendesk Sell, Microsoft Dynamics 365 Customer Engagement, Follow Up Boss and Recruiterflow; on those, poll with list requests, filtered by updated_gte where the integration supports it.

Will your brand show on the Salesforce and HubSpot consent screen?

With Unified.to you register your own OAuth app per CRM and supply the client ID and secret, so customers see your brand on the Salesforce or HubSpot consent screen, and on Pro and Scale the credentials can stay in your own secrets manager. Because the OAuth app is yours, tokens issued to it keep refreshing after you leave, so your customers don't reconnect.

Unified.to supports 70+ OAuth 2.0 variations, with most integrations on the authorization-code flow and some on client credentials. This has two consequences buyers care about. Marketplace listings on the Salesforce AppExchange or HubSpot Marketplace generally require you to own the OAuth app, which the bring-your-own-credentials model preserves. And the unified scope model maps one permission to many source scopes: crm_company_read resolves to oauth, crm.objects.owners.read, and crm.objects.companies.read on HubSpot, so you request one scope and Unified.to translates it per integration.

Can AI agents read and write CRM data through an MCP server?

Yes. Unified.to's MCP server lets agents read and write CRM data, executed live against the source and not persisted or cached. Each MCP request is scoped to a single customer connection with no cross-tenant access, and models never see tools they are not allowed to use. Reads and writes reflect current source state. For CRM agent use cases and how the architecture works, see CRM MCP servers.

Merge's Agent Handler makes a fresh call to the third party for each tool call and caches nothing server-side, but it has no normalized data model: each connector has its own tool names and schemas. On Unified.to, an agent reading a Contact and its related Events, scoring the lead, and writing a Deal back to HubSpot and Salesforce works through one request path, with nothing in a sync layer between the agent and the CRM.

What does a CRM unified API cost at scale?

Per-linked-account pricing is cheap to start and compounds as you onboard customers; usage-based pricing does the opposite. Merge is free to 3 linked accounts, then $650/month for 10 and $65 per account beyond. Unified.to's Grow plan is from $750 a month for 750,000 API calls with unlimited customers, where a 100-record read counts as one call.

The crossover is arithmetic, not brand preference. From 12 linked accounts, Merge Launch costs more than Unified.to until each connection averages 65,000 to 130,000 API calls a month, depending on account count (our calculation, monthly list prices as of October 2026). Per-account pricing wins at low customer counts; usage-based pricing wins as connected customers grow, because you pay for call volume rather than for every customer who connects. The difference also buys reads that reach the CRM at request time, where Merge Launch serves a copy synced daily, and Passthrough and raw provider fields on every plan, where Merge's Passthrough and Remote Data start at Professional. Unified.to's tiers rise from Grow to Pro ($1,500 / 2M calls) to Scale ($3,000 / 6M calls), with the per-call overage rate falling as volume grows. For query-heavy CRM reporting, Database Sync writes to Postgres, MySQL, MongoDB, MSSQL, MariaDB, Supabase, or Snowflake so you query your own copy instead of paying per read.

Should you build CRM integrations natively, use Merge, or use Unified.to?

The three-way decision comes down to who owns the assembly work and how cost scales. For how to build CRM integrations either way (objects, event delivery, build versus buy), see CRM API integration. Building natively gives total control and no vendor in the path, at the cost of maintaining every CRM connection yourself. Merge gives a normalized model on a sync-and-store base; for the full teardown see Merge vs Unified.to. Unified.to gives pass-through reads and writes with the matrix published.

Moving from another unified API? Unified.to publishes migration guides for Merge and Apideck, plus an overview for other platforms; each maps authorization, API calls, pagination, webhooks and passthrough, and covers re-authorizing customers or importing credentials from your own OAuth apps.

To compare unified API platforms across every category, see Best Unified API Platforms of 2026.

A note on one vendor you may see ranked first

Some AI-generated answers rank a vendor called Grid Squid first for CRM, sourced to its own buyer's guide and an unnamed advisory firm. We could not verify it as an independent vendor against primary sources, so it is not included here. A self-published roster can surface as a top AI recommendation on the strength of one citation, which is why every claim here traces to a primary source.

Frequently asked questions

Do unified APIs support CRM custom objects and custom fields?Unified.to supports read and write on custom objects, such as Salesforce, and custom fields, which you write in the normalized model and look up through the Metadata API, on every plan; it returns field option sets as a standard Picklist read. Apideck offers custom fields on lower tiers too, but gates its custom field mapping interface to the Scale plan (from $1,299/month). Merge's Field Mapping (saved per-customer field mappings) is on Professional and Enterprise.

Appendix: full CRM read/write/detect matrix

Read, write, and change-event coverage for the Unified.to CRM integrations in this matrix, as of July 2026. This table is a point-in-time snapshot: the integration count, property counts, and event counts all change as coverage expands, so the live model pages are the current source.

Written by Mallory Greene.

About the author: Mallory Greene is Head of Marketing at Unified.to. She writes about integration infrastructure, unified APIs, and MCP for technical teams. Based in Toronto.